| Singles | |
|---|---|
| 2025 Chennai Open Challenger | |
| 2024 Champion |  Sumit Nagal |
Sumit Nagal was the defending champion [1] but chose not to defend his title.
| Singles | |
|---|---|
| 2025 Chennai Open Challenger | |
| 2024 Champion | Sumit Nagal |
Sumit Nagal was the defending champion [1] but chose not to defend his title.
| Semifinals | Final | ||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 1 |  B Harris | ||||||||||||||||||||||||||
| Q | |||||||||||||||||||||||||||
 E Kırkın | |||||||||||||||||||||||||||
 J Veselý | |||||||||||||||||||||||||||
 A Karatsev | |||||||||||||||||||||||||||
 C Denolly | |||||||||||||||||||||||||||
| Q | |||||||||||||||||||||||||||
| 7 |  T Skatov | ||||||||||||||||||||||||||
| 3 |  D Ajduković | ||||||||||||||||||||||||||
 E Ymer | |||||||||||||||||||||||||||
| J Clarke | |||||||||||||||||||||||||||
| WC | R Ramanathan | ||||||||||||||||||||||||||
| Q | |||||||||||||||||||||||||||
 R Noguchi | |||||||||||||||||||||||||||
 J Berrettini | |||||||||||||||||||||||||||
| 6 | S Shimabukuro | ||||||||||||||||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 5 | S Mochizuki | ||||||||||||||||||||||||||
| E Dalla Valle | |||||||||||||||||||||||||||
 M Geerts | |||||||||||||||||||||||||||
| Q | |||||||||||||||||||||||||||
| K Jacquet | |||||||||||||||||||||||||||
| WC | K Singh | ||||||||||||||||||||||||||
| Q | |||||||||||||||||||||||||||
| 4 |  A Galarneau | ||||||||||||||||||||||||||
| 8 |  Z Piros | ||||||||||||||||||||||||||
 O Ovcharenko | |||||||||||||||||||||||||||
| A Zakharov | |||||||||||||||||||||||||||
| WC | M Sasikumar | ||||||||||||||||||||||||||
 K Sultanov | |||||||||||||||||||||||||||
| D Svrčina | |||||||||||||||||||||||||||
| Q | |||||||||||||||||||||||||||
| 2 |  L Harris | ||||||||||||||||||||||||||
Orlando Luz and Marcelo Zormann were the defending champions, but they chose to participate at the Pan American Games instead.
Lý Hoàng Nam and Sumit Nagal were the defending champions, but were both ineligible to compete this year.
Stefano Travaglia was the defending champion but chose not to defend his title.
Dominic Thiem was the defending champion, but he chose not to defend his title this year.
Nikoloz Basilashvili was the defending champion and successfully defended his title, defeating Andrey Rublev in the final, 7–5, 4–6, 6–3. En route to doing so, Basilashvili saved two match points against Alexander Zverev in the semifinals.
Alessandro Giannessi was the defending champion but chose not to defend his title.
Pablo Andújar was the defending champion but chose not to defend his title.
Cristian Garín was the defending champion, but chose not to defend his title.
Diego Schwartzman defeated Francisco Cerúndolo in the final, 6–1, 6–2 to win the men's singles tennis title at the 2021 Argentina Open.
Lorenzo Sonego defeated defending champion Laslo Đere in the final, 2–6, 7–6(7–5), 6–4 to win the men's singles title at the 2021 Sardegna Open. With the victory, Sonego became the first Italian in 15 years to capture an ATP Tour title on home soil.
Andrey Rublev was the defending champion, but chose to not defend his title as he and other Russian Olympic athletes were sent to Yuzhno-Sakhalinsk for training sessions.
Tallon Griekspoor was the defending champion but chose not to defend his title.
Sumit Nagal was the defending champion but chose not to defend his title.
Sumit Nagal was the defending champion but chose not to defend his title.
Andy Murray was the reigning champion but withdrew before the tournament began.
Matteo Arnaldi was the defending champion but chose not to defend his title.
Dalibor Svrčina was the defending champion but lost in the second round to Lukas Neumayer.
Nicolas Moreno de Alboran was the defending champion but chose not to defend his title.
Filip Misolic was the defending champion but lost in the second round to Oriol Roca Batalla.
Mariano Navone was the defending champion but chose not to defend his title.