| Singles | |
|---|---|
| 2016 "GDD CUP" International Challenger Guangzhou | |
| Champion |  Nikoloz Basilashvili |
| Runner-up |  Lukáš Lacko |
| Score | 6–1, 6–7(6–8), 7–5 |
Kimmer Coppejans was the defending champion but lost to Go Soeda in the second round.
Nikoloz Basilashvili won the title after defeating Lukáš Lacko 6–1, 6–7(6–8), 7–5 in the final.
Taro Daniel (first round)
Dudi Sela (semifinals, retired)
Daniel Gimeno Traver (first round)
Filip Krajinović (first round) Lukáš Lacko (final)
Yuki Bhambri (second round, retired) Nikoloz Basilashvili (champion)
Kimmer Coppejans (second round)| Semifinals | Final | ||||||||||||
| SE |  Zhang Ze | 0 | 1 | ||||||||||
| 5 | Lukáš Lacko | 6 | 6 | ||||||||||
| 5 | Lukáš Lacko | 1 | 78 | 5 | |||||||||
| 7 | Nikoloz Basilashvili | 6 | 66 | 7 | |||||||||
| 7 | Nikoloz Basilashvili | 65 | 6 | 2 | |||||||||
| 2 | Dudi Sela | 77 | 4 | 0r | |||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 1 | T Daniel | 6 | 0 | 5 | |||||||||||||||||||||||
| S Myneni | 1 | 6 | 7 | S Myneni | 6 | 65 | 2 | ||||||||||||||||||||
| SE | Z Zhang | 7 | 6 | SE | Z Zhang | 4 | 77 | 6 | |||||||||||||||||||
 L Saville | 5 | 3 | SE | Z Zhang | 6 | 6 | |||||||||||||||||||||
| WC | Z Li | 6 | 65 | 6 | WC | Z Li | 2 | 4 | |||||||||||||||||||
 A Kudryavtsev | 1 | 77 | 1 | WC | Z Li | 4 | |||||||||||||||||||||
| Q |  L Sonego | 1 | 1 | 6 | Y Bhambri | 1r | |||||||||||||||||||||
| 6 | Y Bhambri | 6 | 6 | SE | Z Zhang | 0 | 1 | ||||||||||||||||||||
| 3 | D Gimeno Traver | 3 | 3 | 5 | L Lacko | 6 | 6 | ||||||||||||||||||||
 A Pavlásek | 6 | 6 | A Pavlásek | 6 | 67 | 2 | |||||||||||||||||||||
 P Gojowczyk | 6 | 3 | 3 |  M İlhan | 3 | 79 | 6 | ||||||||||||||||||||
| M İlhan | 1 | 6 | 6 | M İlhan | 6 | 3 | 4 | ||||||||||||||||||||
| WC | A Çelikbilek | 2 | 2 | 5 | L Lacko | 4 | 6 | 6 | |||||||||||||||||||
| N Langer | 6 | 6 | N Langer | 3 | 4 | ||||||||||||||||||||||
| Q |  M Neuchrist | 2 | 2 | 5 | L Lacko | 6 | 6 | ||||||||||||||||||||
| 5 | L Lacko | 6 | 6 | ||||||||||||||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 7 | N Basilashvili | 5 | 7 | 6 | |||||||||||||||||||||||
 B Rola | 7 | 5 | 4 | 7 | N Basilashvili | 7 | 6 | ||||||||||||||||||||
| Q |  M Copil | 0 | 2 |  M Chiudinelli | 5 | 0 | |||||||||||||||||||||
| M Chiudinelli | 6 | 6 | 7 | N Basilashvili | 67 | 6 | 6 | ||||||||||||||||||||
 F Škugor | 6 | 1 | F Škugor | 79 | 4 | 2 | |||||||||||||||||||||
| WC | Y Bai | 3 | 0r | F Škugor | 6 | 6 | |||||||||||||||||||||
| T Fabbiano | 77 | 6 | T Fabbiano | 4 | 3 | ||||||||||||||||||||||
| 4 | F Krajinović | 62 | 4 | 7 | N Basilashvili | 65 | 6 | 2 | |||||||||||||||||||
| 8 | K Coppejans | 6 | 6 | 2 | D Sela | 77 | 4 | 0r | |||||||||||||||||||
| Q |  J Wang | 2 | 2 | 8 | K Coppejans | 3 | 1 | ||||||||||||||||||||
| WC | C Wang | 3 | 3 | G Soeda | 6 | 6 | |||||||||||||||||||||
| G Soeda | 6 | 6 | G Soeda | 6 | 2 | 3 | |||||||||||||||||||||
| D Wu | 6 | 6 | 2 | D Sela | 4 | 6 | 6 | ||||||||||||||||||||
| J Thompson | 3 | 2 | D Wu | 2 | 0 | ||||||||||||||||||||||
| H Moriya | 4 | 6 | 5 | 2 | D Sela | 6 | 6 | ||||||||||||||||||||
| 2 | D Sela | 6 | 1 | 7 | |||||||||||||||||||||||
Bjorn Fratangelo was the defending champion, but was not eligible to participate.
Kimmer Coppejans won this event, defeating 5th-seed Filip Peliwo 6–1, 6–4 in the final.
Gaël Monfils was the defending champion, but lost to Richard Gasquet in the semifinals.
Gasquet went on to win the title, defeating Jerzy Janowicz in the final, 3–0, ret.
Nikoloz Basilashvili won the title, defeating Lukáš Lacko in the final, 4–6, 6–4, 6–3.
Damir Džumhur was the defending champion but lost in the second round.
Lukáš Rosol was the defending champion but chose not to compete.
Players and pairs who neither have high enough rankings nor receive wild cards may participate in a qualifying tournament held one week before the annual Wimbledon Tennis Championships.
Blaž Kavčič was the defending champion, but chose not to compete.
2nd seed Mikhail Youzhny won his fifth career ATP Challenger Tour title, beating Marco Chiudinelli 6–4, 6–4. This was Youzhny's third consecutive ATP Challenger title, having won the KPN Bangkok Open and the KPN Bangkok Open II in the previous two weeks.
Blaž Kavčič was the defending champion, but did not compete this year.
Nikoloz Basilashvili was the defending champion, but chose not to defend his title.
Philipp Kohlschreiber was the defending champion, but lost in the second round to Karen Khachanov.
Lukáš Lacko was the defending champion but lost in the quarterfinals to Cem İlkel.
This was the first edition of the tournament.
Borna Ćorić defeated the defending champion Roger Federer in the final, 7–6(8–6), 3–6, 6–2 to win the singles tennis title at the 2018 Halle Open. It was his first ATP 500 title. With Federer's loss, Rafael Nadal regained the world No. 1 ranking.
Leonardo Mayer was the defending champion, but lost in the final to Nikoloz Basilashvili, 4–6, 6–0, 5–7. This was Basilashvili's first ATP World Tour title, as well as the first ATP title won by a Georgian player since Alexander Metreveli.
Mirza Bašić was the defending champion but lost in the first round to Martin Kližan.
This was the first edition of the tournament.
Nikoloz Basilashvili defeated Roberto Bautista Agut in the final, 7–6(7–5), 6–2 to win the men's singles tennis title at the 2021 Qatar Open. Basilashvili saved a match point against Roger Federer in the quarterfinals.
Ugo Humbert defeated Andrey Rublev in the final 6–3, 7–6(7–4), to win the singles tennis title at the 2021 Halle Open. Humbert's win earned him his third career ATP Tour singles title and his first ATP 500 victory, and also made him the first French player to win the tournament since Henri Leconte won the inaugural edition in 1993. Both Humbert and Rublev were contesting their first career final on grass.