| Singles | |
|---|---|
| 2023 Sparkassen ATP Challenger | |
| Champion |  Lukáš Klein |
| Runner-up |  Maks Kaśnikowski |
| Score | 6–7(4–7), 7–6(7–4), 7–6(8–6) |
Borna Gojo was the defending champion [1] but chose not to defend his title.
Lukáš Klein won the title after defeating Maks Kaśnikowski 6–7(4–7), 7–6(7–4), 7–6(8–6) in the final.
Abdullah Shelbayh (second round)
Gauthier Onclin (first round)
Federico Gaio (semifinals) Francesco Maestrelli (first round)
Mark Lajal (second round)
Alejandro Moro Cañas (first round) Stefano Napolitano (first round)
Illya Marchenko (second round)| Semifinals | Final | ||||||||||||
| Q | Lukáš Klein | 6 | 77 | ||||||||||
 Billy Harris | 3 | 65 | |||||||||||
| Q | Lukáš Klein | 64 | 77 | 78 | |||||||||
| Maks Kaśnikowski | 77 | 64 | 66 | ||||||||||
| 3 | Federico Gaio | 3 | 7 | 2 | |||||||||
| Maks Kaśnikowski | 6 | 5 | 6 | ||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 1 | A Shelbayh | 6 | 6 | ||||||||||||||||||||||||
 M Efstathiou | 1 | 2 | 1 | A Shelbayh | 6 | 3 | 4 | ||||||||||||||||||||
 Y Demin | 63 | 4 | Alt | E Dalla Valle | 4 | 6 | 6 | ||||||||||||||||||||
| Alt | E Dalla Valle | 77 | 6 | Alt | E Dalla Valle | 3 | 2 | ||||||||||||||||||||
| Alt |  A Paulson | 5 | 4 | Q | L Klein | 6 | 6 | ||||||||||||||||||||
| Q | L Klein | 7 | 6 | Q | L Klein | 77 | 77 | ||||||||||||||||||||
| Q |  M Bašić | 77 | 6 | Q | M Bašić | 65 | 63 | ||||||||||||||||||||
| 6 | A Moro Cañas | 63 | 3 | Q | L Klein | 6 | 77 | ||||||||||||||||||||
| 4 | F Maestrelli | 6 | 64 | 1 | B Harris | 3 | 65 | ||||||||||||||||||||
 A Bellier | 4 | 77 | 6 | A Bellier | 4 | 4 | |||||||||||||||||||||
| Q |  Ryan Nijboer | 3 | 67 | Q | D Glinka | 6 | 6 | ||||||||||||||||||||
| Q | D Glinka | 6 | 79 | Q | D Glinka | 63 | 6 | 3 | |||||||||||||||||||
| Q | Hynek Bartoň | 65 | 77 | 6 | B Harris | 77 | 4 | 6 | |||||||||||||||||||
| D Jordà Sanchis | 77 | 64 | 3 | Q | H Bartoň | 2 | 63 | ||||||||||||||||||||
| B Harris | 7 | 6 | B Harris | 6 | 77 | ||||||||||||||||||||||
| 7 | S Napolitano | 5 | 3 | ||||||||||||||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 8 | I Marchenko | 6 | 6 | ||||||||||||||||||||||||
| WC | L Rottoli | 4 | 4 | 8 | I Marchenko | 6 | 2 | 65 | |||||||||||||||||||
| Q | Luca Giacomini | 6 | 6 | Q | L Giacomini | 4 | 6 | 77 | |||||||||||||||||||
 L Wessels | 3 | 4 | Q | L Giacomini | 63 | 62 | |||||||||||||||||||||
| WC | F Forti | 77 | 6 | 3 | F Gaio | 77 | 77 | ||||||||||||||||||||
| N Gombos | 65 | 4 | WC | F Forti | 6 | 3 | 3 | ||||||||||||||||||||
 M Neuchrist | 4 | 4 | 3 | F Gaio | 3 | 6 | 6 | ||||||||||||||||||||
| 3 | F Gaio | 6 | 6 | 3 | F Gaio | 3 | 7 | 2 | |||||||||||||||||||
| 5 | M Lajal | 6 | 6 | M Kaśnikowski | 6 | 5 | 6 | ||||||||||||||||||||
| K Żuk | 3 | 4 | 5 | M Lajal | 6 | 4 | 2 | ||||||||||||||||||||
 M Bourgue | 6 | 66 | 6 | M Bourgue | 3 | 6 | 6 | ||||||||||||||||||||
 J Sousa | 3 | 78 | 4 | M Bourgue | 63 | 3 | |||||||||||||||||||||
| M Geerts | 6 | 6 | M Kaśnikowski | 77 | 6 | ||||||||||||||||||||||
| WC | Lorenzo Carboni | 4 | 1 | M Geerts | 7 | 3 | 64 | ||||||||||||||||||||
| M Kaśnikowski | 6 | 6 | M Kaśnikowski | 5 | 6 | 77 | |||||||||||||||||||||
| 2 | G Onclin | 1 | 4 | ||||||||||||||||||||||||
Daniil Medvedev was the defending champion, but chose not to participate this year.
Henri Laaksonen was the defending champion but chose not to defend his title.
Evgeny Donskoy was the defending champion but chose not to defend his title.
Roberto Bautista Agut was the defending champion but chose not to defend his title.
Andrey Rublev was the reigning champion from when the tournament was last held in 2019, but lost to Adrian Mannarino in the second round in a rematch of the 2019 final.
Jack Draper was the defending champion but lost in the first round to Borna Gojo.
James Duckworth was the defending champion but chose not to defend his title.
Tseng Chun-hsin was the defending champion but lost in the first round to Markos Kalovelonis.
Nick Kyrgios defeated Yoshihito Nishioka in the final, 6–4, 6–3 to win the men's singles tennis title at the 2022 Washington Open. It was his second Washington title, following 2019. Kyrgios saved five match points en route to the title, in the quarterfinals against Frances Tiafoe. He also did not drop serve during the tournament.
Félix Auger-Aliassime defeated J. J. Wolf in the final, 6–4, 6–4 to win the singles tennis title at the 2022 Firenze Open. It was his second ATP Tour singles title.
Lorenzo Musetti defeated Matteo Berrettini in the final, 7–6(7–5), 6–2 to win the singles tennis title at the 2022 Napoli Cup. It was his second career ATP Tour singles title.
Brandon Nakashima was the defending champion but chose not to defend his title.
Oscar Otte was the defending champion but chose not to defend his title.
Tallon Griekspoor was the defending champion but chose not to defend his title.
Fernando Verdasco was the defending champion but chose not to defend his title.
Tseng Chun-hsin was the defending champion but chose not to defend his title.
Pedro Cachin was the defending champion but lost in the final to Alexander Shevchenko.
Roberto Carballés Baena was the defending champion but chose not to defend his title.
Frances Tiafoe defeated Jan-Lennard Struff in the final, 4–6, 7–6(7–1), 7–6(10–8) to win the singles title at the 2023 Stuttgart Open. It was his third ATP Tour title, and his first on grass courts. Tiafoe saved a championship point en route to the title, in the final-set tiebreak. By winning the title, Tiafoe debuted in the top ten of the ATP rankings for the first time in his career.
Francisco Cerúndolo won the men's singles title, defeating Tommy Paul in the final, 6–4, 1–6, 6–4.