2021 Kremlin Cup
The 2021 Kremlin Cup was a professional tennis tournament played on indoor hard courts. It was the 31st edition of the Kremlin Cup for the men and the 25th edition for the women. The tournament was part of the ATP 250 series of the 2021 ATP Tour, and of the WTA 500 series of the 2021 WTA Tour. It was held at the Irina Viner-Usmanova Gymnastics Palace and the Luzhniki Palace of Sports in Moscow, Russia, from 18 October through 24 October 2021.
Champions
Men's singles
- Aslan Karatsev def. Marin Čilić, 6–2, 6–4
Women's singles
- Anett Kontaveit def. Ekaterina Alexandrova, 4–6, 6–4, 7–5.
Men's doubles
- Harri Heliövaara / Matwé Middelkoop def. Tomislav Brkić / Nikola Ćaćić, 7–5, 4–6,
Women's doubles
- Jeļena Ostapenko / Kateřina Siniaková def. Nadiia Kichenok / Raluca Olaru, 6–2, 4–6,
ATP singles main-draw entrants
Seeds
- Rankings are as of October 4, 2021
Other entrants
The following players received entry using a protected ranking:
The following players received entry from the qualifying draw:
The following player received entry as a lucky loser:
- Ričardas Berankis
Withdrawals
- Pablo Andújar → replaced by Federico Coria
- Ilya Ivashka → replaced by Ričardas Berankis
- Sebastian Korda → replaced by Gilles Simon
- Daniil Medvedev → replaced by Mikael Ymer
ATP doubles main-draw entrants
Seeds
| Country | Player | Country | Player | Rank1 | Seed | ||
 South AfricaOther entrantsThe following pairs received wildcards into the doubles main draw:
Seeds
The following player received entry as a lucky loser:
Seeds
|
Chile