Kiki Bertens career statistics

Career finals
Discipline	Type	Won	Lost	Total	WR
Singles	Grand Slam	–	–	–	–
	Summer Olympics	–	–	–	–
	WTA Finals [lower-alpha 1]	–	–	–	–
	WTA Elite [lower-alpha 2]	0	1	1	0.00
	WTA 1000 [lower-alpha 3]	2	1	3	0.67
	WTA 500 [lower-alpha 4]	3	0	3	1.00
	WTA 250 [lower-alpha 5]	5	3	8	0.63
	Total	10	5	15	0.67
Doubles	Grand Slam	–	–	–	–
	Summer Olympics	–	–	–	–
	WTA Finals [lower-alpha 1]	0	1	1	0.00
	WTA Elite [lower-alpha 2]	–	–	–	–
	WTA 1000 [lower-alpha 3]	–	–	–	–
	WTA 500 [lower-alpha 4]	1	1	2	0.50
	WTA 250 [lower-alpha 5]	9	4	13	0.69
	Total	10	6	16	0.63
Total		20	8	28	0.71

This is a list of the main career statistics of professional Dutch tennis player Kiki Bertens . ^[1]

Bertens at the 2018 French Open

Performance timelines

Key

W

F

SF

QF

#R

RR

Q#

P#

DNQ

A

Z#

PO

G

S

B

NMS

NTI

P

NH

(W) winner; (F) finalist; (SF) semifinalist; (QF) quarterfinalist; (#R) rounds 4, 3, 2, 1; (RR) round-robin stage; (Q#) qualification round; (P#) preliminary round; (DNQ) did not qualify; (A) absent; (Z#) Davis/Fed Cup Zonal Group (with number indication) or (PO) play-off; (G) gold, (S) silver or (B) bronze Olympic/Paralympic medal; (NMS) not a Masters tournament; (NTI) not a Tier I tournament; (P) postponed; (NH) not held; (SR) strike rate (events won / competed); (W–L) win–loss record.

To avoid confusion and double counting, these charts are updated at the conclusion of a tournament or when the player's participation has ended.

Only main-draw results in WTA Tour, Grand Slam tournaments, Billie Jean King Cup (Fed Cup), Hopman Cup and Olympic Games are included in win–loss records. ^[2]

Singles

Current through Tennis at the 2020 Summer Olympics.

Tournament	2011	2012	2013	2014	2015	2016	2017	2018	2019	2020	2021	SR	W–L	Win %
Grand Slam tournaments
Australian Open	A	Q2	1R	1R	2R	1R	1R	3R	2R	4R	A	0 / 8	7–8	47%
French Open	Q1	1R	1R	4R	1R	SF	2R	3R	2R	4R	1R	0 / 10	15–10	60%
Wimbledon	A	2R	1R	Q1	1R	3R	1R	QF	3R	NH	1R	0 / 8	9–8	53%
US Open	Q1	2R	1R	1R	2R	1R	1R	3R	3R	A	A	0 / 8	6–8	43%
Win–loss	0–0	2–3	0–4	3–3	2–4	7–4	1–4	10–4	6–4	6–2	0–2	0 / 34	37–34	52%
Year-end championships
WTA Finals	did not qualify							SF	RR	NH	DNQ	0 / 2	3–3	50%
WTA Elite Trophy	did not qualify					RR	DNQ	A	F	NH	DNQ	0 / 2	3–3	50%
National representation
Summer Olympics	NH	A	not held			1R	not held				1R	0 / 2	0–2	0%
Billie Jean King Cup	Z1	Z1	A	Z1	PO	SF	1R	A	A	PO	A	0 / 2	19–2	90%
WTA 1000
Dubai / Qatar Open [lower-alpha 6]	A	A	A	A	A	A	1R	A	2R	3R	2R	0 / 4	1–4	20%
Indian Wells Open	A	A	2R	A	1R	1R	3R	2R	4R	NH	A	0 / 6	6–7	46%
Miami Open	A	A	2R	2R	1R	3R	2R	3R	4R	NH	2R	0 / 8	7–8	47%
Madrid Open	A	A	1R	A	A	A	QF	F	W	NH	2R	1 / 5	15–4	79%
Italian Open	A	A	2R	A	A	1R	SF	1R	SF	2R	A	0 / 6	7–6	54%
Canadian Open	A	2R	2R	1R	A	A	A	QF	3R	NH	A	0 / 5	6–5	55%
Cincinnati Open	A	1R	A	Q1	A	1R	2R	W	2R	A	A	1 / 5	7–4	64%
Pan Pacific / Wuhan Open [lower-alpha 7]	A	A	A	A	A	A	2R	2R	3R	not held		0 / 3	3–3	50%
China Open	A	A	A	A	A	A	1R	3R	SF	not held		0 / 3	6–3	67%
Career statistics
	2011	2012	2013	2014	2015	2016	2017	2018	2019	2020	2021	SR	W–L	Win %
Tournaments	1	13	19	14	17	20	28	25	28	7	8	Career total: 180
Titles	0	1	0	0	0	1	2	3	2	1	0	Career total: 10
Finals	0	1	0	0	0	2	2	4	5	1	0	Career total: 15
Hard win–loss	0–0	5–7	8–9	5–10	3–12	9–14	8–17	26–15	29–18	10–3	0–4	4 / 110	103–109	49%
Clay win–loss	0–0	5–3	6–8	6–4	4–4	19–5	24–6	15–5	17–5	5–3	2–2	6 / 51	103–45	70%
Grass win–loss	0–1	1–2	0–2	0–0	3–2	2–1	0–3	5–3	9–3	0–0	0–2	0 / 19	20–19	51%
Overall win–loss	0–1	11–12	14–19	11–14	10–18	30–20	32–26	46–23	55–26	15–6	2–8	10 / 180	226–173	57%
Win (%)	0%	48%	42%	44%	36%	60%	55%	67%	68%	71%	20%	Career total: 57%
Year-end ranking	184	63	87	69	101	22	31	9	9	9	NR	$11,425,132

Doubles

Tournament	2012	2013	2014	2015	2016	2017	2018	2019	2020	2021	SR	W–L
Grand Slam tournaments
Australian Open	A	1R	1R	QF	1R	2R	1R	A	A	A	0 / 6	4–6
French Open	1R	1R	A	1R	QF	3R	3R	A	A	A	0 / 6	7–6
Wimbledon	A	A	A	1R	2R	1R	3R	A	NH	1R	0 / 5	3–5
US Open	1R	2R	1R	3R	2R	3R	2R	A	A	A	0 / 7	7–7
Win–loss	0–2	1–3	0–2	5–4	5–4	5–4	5–4	0–0	0–0	0–1	0 / 24	21–24
Year-end championships
WTA Finals	did not qualify					F	DNQ		NH	DNQ	0 / 1	2–1
Career statistics
Titles	0	0	0	2	3	4	1	0	0	0	Career total: 10
Finals	0	0	0	3	4	6	2	0	1	0	Career total: 16
Year-end ranking	296	326	251	38	37	19	43	178	116	99

Significant finals

Year-end championships

Doubles: 1 (runner-up)

Result	Year	Tournament	Surface	Partner	Opponents	Score
Loss	2017	WTA Finals, Singapore	Hard (i)	Johanna Larsson	Tímea Babos Andrea Hlaváčková	6–4, 4–6, [5–10]

WTA Elite Trophy

Singles: 1 (runner-up)

Result	Year	Venue	Surface	Opponent	Score
Loss	2019	Elite Trophy, Zhuhai	Hard (i)	Aryna Sabalenka	4–6, 2–6

WTA 1000

Singles: 3 (2 titles, 1 runner-up)

Result	Year	Tournament	Surface	Opponent	Score
Loss	2018	Madrid Open	Clay	Petra Kvitová	6–7(6–8), 6–4, 3–6
Win	2018	Cincinnati Open	Hard	Simona Halep	2–6, 7–6(8–6), 6–2
Win	2019	Madrid Open	Clay	Simona Halep	6–4, 6–4

WTA Tour finals

Singles: 15 (10 titles, 5 runner-ups)

Legend WTA Elite (0–1) WTA 1000 (Premier 5 / Premier M) (2–1) WTA 500 (Premier) (3–0) WTA 250 (International) (5–3)

Finals by surface Hard (4–1) Clay (6–3) Grass (0–1)

Result	W–L	Date	Tournament	Tier	Surface	Opponent	Score
Win	1–0	Apr 2012	Morocco Open, Morocco	International	Clay	Laura Pous Tió	7–5, 6–0
Win	2–0	May 2016	Nuremberg Cup, Germany	International	Clay	Mariana Duque Mariño	6–2, 6–2
Loss	2–1	Jul 2016	Swiss Open, Switzerland	International	Clay	Viktorija Golubic	6–4, 3–6, 4–6
Win	3–1	May 2017	Nuremberg Cup, Germany (2)	International	Clay	Barbora Krejčíková	6–2, 6–1
Win	4–1	Jul 2017	Swiss Open, Switzerland	International	Clay	Anett Kontaveit	6–4, 3–6, 6–1
Win	5–1	Apr 2018	Charleston Open, United States	Premier	Clay	Julia Görges	6–2, 6–1
Loss	5–2	May 2018	Madrid Open, Spain	Premier M	Clay	Petra Kvitová	6–7(6–8), 6–4, 3–6
Win	6–2	Aug 2018	Cincinnati Open, United States	Premier 5	Hard	Simona Halep	2–6, 7–6(8–6), 6–2
Win	7–2	Sep 2018	Korea Open, South Korea	International	Hard	Ajla Tomljanović	7–6(7–2), 4–6, 6–2
Win	8–2	Feb 2019	St. Petersburg Trophy, Russia	Premier	Hard (i)	Donna Vekić	7–6(7–2), 6–4
Win	9–2	May 2019	Madrid Open, Spain	Premier M	Clay	Simona Halep	6–4, 6–4
Loss	9–3	Jun 2019	Rosmalen Open, Netherlands	International	Grass	Alison Riske	6–0, 6–7(3–7), 5–7
Loss	9–4	Jul 2019	Palermo Ladies Open, Italy	International	Clay	Jil Teichmann	6–7(3–7), 2–6
Loss	9–5	Oct 2019	WTA Elite Trophy, China	Elite	Hard (i)	Aryna Sabalenka	4–6, 2–6
Win	10–5	Feb 2020	St. Petersburg Trophy, Russia (2)	Premier	Hard (i)	Elena Rybakina	6–1, 6–3

Doubles: 16 (10 titles, 6 runner-ups)

Legend WTA Finals (0–1) WTA 500 (Premier) (1–1) WTA 250 (International) (9–4)

Finals by surface Hard (7–4) Grass (0–2) Clay (3–0)

Result	W–L	Date	Tournament	Tier	Surface	Partner	Opponents	Score
Win	1–0	Jan 2015	Hobart International, Australia	International	Hard	Johanna Larsson	Vitalia Diatchenko Monica Niculescu	7–5, 6–3
Win	2–0	Jul 2015	Swedish Open, Sweden	International	Clay	Johanna Larsson	Tatjana Maria Olga Savchuk	7–5, 6–4
Loss	2–1	Sep 2015	Korea Open, South Korea	International	Hard	Johanna Larsson	Lara Arruabarrena Andreja Klepač	6–2, 3–6, [6–10]
Loss	2–2	Feb 2016	Mexican Open, Mexico	International	Hard	Johanna Larsson	Anabel Medina Garrigues Arantxa Parra Santonja	0–6, 4–6
Win	3–2	May 2016	Nuremberg Cup, Germany	International	Clay	Johanna Larsson	Shuko Aoyama Renata Voráčová	6–3, 6–4
Win	4–2	Oct 2016	Linz Open, Austria	International	Hard (i)	Johanna Larsson	Anna-Lena Grönefeld Květa Peschke	4–6, 6–2, [10–7]
Win	5–2	Oct 2016	Luxembourg Open, Luxembourg	International	Hard (i)	Johanna Larsson	Monica Niculescu Patricia Maria Țig	4–6, 7–5, [11–9]
Win	6–2	Jan 2017	Auckland Open, New Zealand	International	Hard	Johanna Larsson	Demi Schuurs Renata Voráčová	6–2, 6–2
Loss	6–3	Jun 2017	Rosmalen Open, Netherlands	International	Grass	Demi Schuurs	Dominika Cibulková Kirsten Flipkens	6–4, 4–6, [6–10]
Win	7–3	Jul 2017	Swiss Open, Switzerland	International	Clay	Johanna Larsson	Viktorija Golubic Nina Stojanović	7–6(7–4), 4–6, [10–7]
Win	8–3	Sep 2017	Korea Open, South Korea	International	Hard	Johanna Larsson	Luksika Kumkhum Peangtarn Plipuech	6–4, 6–1
Win	9–3	Oct 2017	Linz Open, Austria (2)	International	Hard (i)	Johanna Larsson	Natela Dzalamidze Xenia Knoll	3–6, 6–3, [10–4]
Loss	9–4	Oct 2017	WTA Finals, Singapore	Finals	Hard (i)	Johanna Larsson	Tímea Babos Andrea Hlaváčková	6–4, 4–6, [5–10]
Win	10–4	Jan 2018	Brisbane International, Australia	Premier	Hard	Demi Schuurs	Andreja Klepač María José Martínez Sánchez	7–5, 6–2
Loss	10–5	Jun 2018	Rosmalen Open, Netherlands	International	Grass	Kirsten Flipkens	Elise Mertens Demi Schuurs	3–3 ret.
Loss	10–6	Jan 2020	Brisbane International, Australia	Premier	Hard	Ashleigh Barty	Hsieh Su-wei Barbora Strýcová	6–3, 6–7(7–9), [8–10]

ITF Circuit finals

Singles: 11 (7 titles, 4 runner–ups)

Legend $25,000 tournaments $10,000 tournaments

Finals by surface Hard (2–1) Clay (5–3)

Result	W–L	Date	Tournament	Tier	Surface	Opponent	Score
Loss	0–1	Jun 2009	ITF Apeldoorn, Netherlands	10,000	Clay	Natalie Piquion	3–6, 2–6
Win	1–1	Sep 2009	ITF Almere, Netherlands	10,000	Clay	Angelique van der Meet	6–2, 6–4
Win	2–1	Oct 2009	ITF Antalya, Turkey	10,000	Clay	Nanuli Pipiya	6–2, 6–2
Loss	2–2	Feb 2010	ITF Portimão, Portugal	10,000	Hard	Claudia Giovine	3–6, 6–2, 7–6(7–1)
Loss	2–3	Jun 2010	ITF Apeldoorn, Netherlands	10,000	Clay	Angelique van der Meet	5–7, 3–6
Win	3–3	Jun 2010	ITF Rotterdam, Netherlands	10,000	Clay	Daniëlle Harmsen	6–4, 6–2
Loss	3–4	Aug 2010	ITF Koksijde, Belgium	25,000	Clay	Katarzyna Piter	4–6, 4–6
Win	4–4	Aug 2011	ITF Koksijde, Belgium	25,000	Clay	Elitsa Kostova	6–2, 6–1
Win	5–4	Mar 2012	ITF Irapuato, Mexico	25,000	Hard	Yaroslava Shvedova	6–4, 2–6, 6–1
Win	6–4	Mar 2012	GB Pro-Series Bath, United Kingdom	25,000	Hard (i)	Annika Beck	6–4, 3–6, 6–3
Win	7–4	Aug 2015	ITF Koksijde, Belgium (2)	25,000	Clay	Myrtille Georges	3–6, 6–2, 6–3

Doubles: 13 (11 titles, 2 runner–ups)

Legend $100,000 tournaments $75,000 tournaments $50,000 tournaments $25,000 tournaments $10,000 tournaments

Finals by surface Hard (2–2) Clay (8–0) Carpet (1–0)

Result	W–L	Date	Tournament	Tier	Surface	Partner	Opponents	Score
Win	1–0	Aug 2009	ITF Bree, Belgium	10,000	Clay	Quirine Lemoine	An-Sophie Mestach Demi Schuurs	6–1, 6–0
Win	2–0	Aug 2009	ITF Rebecq, Belgium	10,000	Clay	Nicole Thyssen	Patricia Chirea Valentina Sulpizio	6–2, 7–5
Win	3–0	Sep 2009	ITF Almere, Netherlands	10,000	Clay	Nicole Thyssen	Daniëlle Harmsen Kim Kilsdonk	4–6, 6–2, [10–4]
Win	4–0	Oct 2009	ITF Antalya, Turkey	10,000	Clay	Marcella Koek	Barbara Sobaszkiewicz Sylwia Zagórska	6–4, 0–6, [10–4]
Win	5–0	Nov 2009	ITF Jersey, United Kingdom	10,000	Hard (i)	Daniëlle Harmsen	Tímea Babos Malou Ejdesgaard	7–5, 7–5
Win	6–0	Mar 2010	ITF Antalya, Turkey	10,000	Clay	Daniëlle Harmsen	Fatma Al-Nabhani Andrea Koch Benvenuto	6–2, 6–4
Win	7–0	Oct 2010	ITF Helsinki, Finland	25,000	Hard (i)	Richèl Hogenkamp	Yuliya Beygelzimer Kristina Mladenovic	6–3, 7–5
Loss	7–1	Jan 2011	Open Andrézieux, France	25,000	Hard (i)	Richèl Hogenkamp	Darija Jurak Valeria Savinykh	3–6, 6–7(0–7)
Win	8–1	Aug 2011	ITF Monteroni, Italy	25,000	Clay	Nicole Rottmann	Gioia Barbieri Anastasia Grymalska	6–0, 6–3
Loss	8–2	Oct 2011	ITF Madrid, Spain	25,000	Hard	Elyne Boeykens	Rocio de la Torre-Sanchez Georgina García Pérez	7–5, 4–6, 2–6
Win	9–2	Nov 2011	Ismaning Open, Germany	50,000	Carpet (i)	Anne Keothavong	Kristina Barrois Yvonne Meusburger	6–3, 6–3
Win	10–2	May 2014	Open de Cagnes-sur-Mer, France	100,000	Clay	Johanna Larsson	Tatiana Búa Daniela Seguel	7–6(7–4), 6–4
Win	11–2	Jul 2015	ITF Warsaw Open, Poland	75,000	Clay	Richèl Hogenkamp	Cornelia Lister Jeļena Ostapenko	7–6(7–2), 6–4

Career Grand Slam statistics

Seedings

The tournaments won by Bertens are in boldface, and advanced into finals by Bertens are in italics.

Year	Australian Open	French Open	Wimbledon	US Open
2011	did not play	did not qualify	did not play	did not qualify
2012	did not qualify	not seeded	not seeded	not seeded
2013	not seeded	not seeded	not seeded	not seeded
2014	not seeded	not seeded	did not qualify	not seeded
2015	not seeded	not seeded	not seeded	not seeded
2016	not seeded	not seeded	26th	20th
2017	19th	18th	23rd	24th
2018	30th	18th	20th	13th
2019	9th	4th	4th	7th
2020	9th	5th	not held	did not play
2021	did not play	16th	17th	did not play

Record against other players

No. 1 wins

No.	Player	Event	Surface	Round	Score	Result
1.	Simona Halep	2018 Cincinnati Open, United States	Hard	F	2–6, 7–6(8–6), 6–2	W
2.	Ashleigh Barty	2019 WTA Finals, Shenzhen	Hard (i)	RR	3–6, 6–3, 6–4	RR

Top 10 wins

Season	2016	2017	2018	2019	2020	Total
Wins	3	0	12	8	0	23

#	Player	vsRank	Event	Surface	Round	Score	Rank
2016
1.	Roberta Vinci	7	Nuremberg Cup, Germany	Clay	2R	6–4, 7–6(7–4)	89
2.	Angelique Kerber	3	French Open, France	Clay	1R	6–2, 3–6, 6–3	58
3.	Timea Bacsinszky	9	French Open, France	Clay	QF	7–5, 6–2	58
2018
4.	Caroline Wozniacki	2	Madrid Open, Spain	Clay	3R	6–2, 6–2	20
5.	Caroline Garcia	7	Madrid Open, Spain	Clay	SF	6–2, 6–2	20
6.	Venus Williams	9	Wimbledon, United Kingdom	Grass	3R	6–2, 6–7(5–7), 8–6	20
7.	Karolína Plíšková	8	Wimbledon, United Kingdom	Grass	4R	6–3, 7–6(7–1)	20
8.	Karolína Plíšková	9	Canadian Open, Canada	Hard	2R	6–2, 6–2	18
9.	Petra Kvitová	8	Canadian Open, Canada	Hard	3R	6–3, 6–2	18
10.	Caroline Wozniacki	2	Cincinnati Open, United States	Hard	2R	6–4, ret.	17
11.	Elina Svitolina	7	Cincinnati Open, United States	Hard	QF	6–4, 6–3	17
12.	Petra Kvitová	6	Cincinnati Open, United States	Hard	SF	3–6, 6–4, 6–2	17
13.	Simona Halep	1	Cincinnati Open, United States	Hard	F	2–6, 7–6(8–6), 6–2	17
14.	Angelique Kerber	2	WTA Finals, Singapore	Hard (i)	RR	1–6, 6–3, 6–4	9
15.	Naomi Osaka	4	WTA Finals, Singapore	Hard (i)	RR	6–3, ret.	9
2019
16.	Aryna Sabalenka	10	St. Petersburg Trophy, Russia	Hard (i)	SF	7–6(7–5), 6–2	8
17.	Angelique Kerber	5	Stuttgart Open, Germany	Clay (i)	QF	6–3, 6–4	7
18.	Petra Kvitová	2	Madrid Open, Spain	Clay	QF	6–2, 6–3	7
19.	Sloane Stephens	8	Madrid Open, Spain	Clay	SF	6–2, 7–5	7
20.	Simona Halep	3	Madrid Open, Spain	Clay	F	6–4, 6–4	7
21.	Aryna Sabalenka	10	Eastbourne International, UK	Grass	QF	6–4, 3–6, 6–4	4
22.	Elina Svitolina	3	China Open, China	Hard	QF	7–6(8–6), 6–2	8
23.	Ashleigh Barty	1	WTA Finals, China	Hard (i)	RR	3–6, 6–3, 6–4	10

Longest winning streaks

10–match (12 with qualifiers) singles winning streak (2016)

#	Tournament	Category	Start date	Surface	Rd	Opponent	Rank	Score
–	Italian Open, Italy	Premier 5	9 May 2016	Clay	1R	Tímea Babos	48	1–6, 4–6
–	Nuremberg Cup, Germany	International	16 May 2016	Clay	Q1	Conny Perrin	229	6–1, 6–0
–					Q2	Cristina Dinu	217	6–1, 6–3
1					1R	Tatjana Maria (Q)	112	6–1, 7–6(7–0)
2					2R	Roberta Vinci (1)	7	6–4, 7–6(7–4)
3					QF	Irina Falconi	64	6–1, 0–1 ret.
4					SF	Julia Görges	60	3–6, 6–4, 7–6(7–4)
5					F	Mariana Duque Mariño	98	6–2, 6–2
6	French Open, France	Grand Slam	23 May 2016	Clay	1R	Angelique Kerber (3)	3	6–2, 3–6, 6–3
7					2R	Camila Giorgi	44	6–4, 6–1
8					3R	Daria Kasatkina (29)	32	6–2, 3–6, 10–8
9					4R	Madison Keys (15)	17	7–6(7–4), 6–3
10					QF	Timea Bacsinszky (8)	9	7–5, 6–2
–					SF	Serena Williams (1)	1	6–7(7–9), 4–6

Notes

1. Formerly known as:
   • Virginia Slims Championships (until 1995)
   • WTA Tour Championships (until 2014)
2. Elite tier:
   • WTA Tournament of Champions (2009–14)
   • WTA Elite Trophy (2015–present)
3. Formerly known as:
   • Category 4 & 5 & 6 (until 1990)
   • Tier I (until 2009)
   • WTA Premier Mandatory and 5 (until 2021)
4. Formerly known as:
   • Category 3 (until 1990)
   • Tier II (until 2009)
   • WTA Premier (until 2021)
5. Formerly known as:
   • Category 1 & 2 (until 1990)
   • Tier III & IV & V (until 2009)
   • WTA International (until 2021)
6. The first Premier 5 event of the year has switched back and forth between the Dubai Tennis Championships and the Qatar Total Open since 2009. Dubai was classified as a Premier 5 event from 2009 to 2011 before being succeeded by Doha for the 2012–2014 period. In 2015, Dubai regained its Premier 5 status while Doha was demoted to Premier status. The Premier 5 tournaments were reclassified as WTA 1000 tournaments in 2021.
7. In 2014, the Pan Pacific Open was downgraded to a Premier event and replaced by the Wuhan Open. The Premier 5 tournaments were reclassified as WTA 1000 tournaments in 2021.

References

1. Player's Profile and Statistics
2. "Player & Career Overview".

External links

• Kiki Bertens at the Women's Tennis Association
• Kiki Bertens at the International Tennis Federation
• Kiki Bertens at the Billie Jean King Cup