2021 MercedesCup

The 2021 MercedesCup was a men's tennis tournament played on outdoor grass courts. It was the 43rd edition of the Stuttgart Open, and part of the ATP Tour 250 series of the 2021 ATP Tour. It was held at the Tennis Club Weissenhof in Stuttgart, Germany, from 8 June until 13 June 2021. Unseeded Marin Čilić won the singles title.

Singles

 * Marin Čilić defeated 🇨🇦 Félix Auger-Aliassime, 7–6(7–2), 6–3

Doubles

 * 🇧🇷 Marcelo Demoliner / 🇲🇽 Santiago González defeated Ariel Behar / 🇪🇨 Gonzalo Escobar, 4–6, 6–3, [10–8]

Prize money

 * per team

Seeds

 * 1 Rankings are as of 31 May 2021.

Other entrants
The following players received wildcards into the main draw:
 * 🇩🇪 Dustin Brown
 * 🇩🇪 Yannick Hanfmann
 * 🇩🇪 Rudolf Molleker
 * 🇦🇹 Jurij Rodionov
 * Dominic Stricker

The following players received entry from the qualifying draw:
 * 🇲🇩 Radu Albot
 * 🇹🇷 Altuğ Çelikbilek
 * 🇦🇺 James Duckworth
 * 🇩🇪 Peter Gojowczyk

The following player received entry as a lucky loser:
 * 🇧🇾 Ilya Ivashka

Withdrawals

 * Before the tournament
 * 🇰🇿 Alexander Bublik → replaced by 🇦🇺 Alexei Popyrin
 * 🇺🇸 Taylor Fritz → replaced by Marin Čilić
 * Cristian Garín → replaced by 🇦🇺 Jordan Thompson
 * 🇷🇺 Aslan Karatsev → replaced by 🇫🇷 Jérémy Chardy
 * 🇺🇸 Reilly Opelka → replaced by Lloyd Harris
 * 🇫🇷 Benoît Paire → replaced by 🇺🇸 Sam Querrey
 * 🇨🇦 Milos Raonic → replaced by 🇭🇺 Márton Fucsovics
 * 🇮🇹 Jannik Sinner → replaced by 🇩🇪 Dominik Koepfer
 * 🇮🇹 Lorenzo Sonego → replaced by 🇦🇷 Guido Pella
 * 🇩🇪 Jan-Lennard Struff → replaced by 🇪🇸 Feliciano López
 * Stan Wawrinka → replaced by 🇧🇾 Ilya Ivashka
 * 🇩🇪 Alexander Zverev → replaced by 🇫🇷 Gilles Simon

Retirements

 * 🇩🇪 Peter Gojowczyk

Seeds

 * 1 Rankings are as of 31 May 2021.

Other entrants
The following pairs received wildcards into the doubles main draw:
 * 🇩🇪 Andre Begemann / 🇩🇪 Dustin Brown
 * 🇩🇪 Yannick Hanfmann / 🇩🇪 Dominik Koepfer

The following pairs received entry as alternates:
 * 🇨🇦 Félix Auger-Aliassime / 🇺🇸 Nicholas Monroe
 * Nikoloz Basilashvili / 🇮🇳 Divij Sharan
 * Ariel Behar / 🇪🇨 Gonzalo Escobar
 * 🇧🇷 Marcelo Demoliner / 🇲🇽 Santiago González
 * 🇦🇷 Máximo González / 🇦🇷 Andrés Molteni
 * 🇵🇱 Hubert Hurkacz / 🇵🇱 Łukasz Kubot
 * 🇦🇹 Oliver Marach / 🇵🇰 Aisam-ul-Haq Qureshi
 * 🇩🇰 Frederik Nielsen / Jean-Julien Rojer
 * 🇦🇺 Luke Saville / 🇦🇺 Jordan Thompson

Withdrawals

 * Before the tournament
 * 🇮🇳 Rohan Bopanna / Franko Škugor → replaced by 🇦🇹 Oliver Marach / 🇵🇰 Aisam-ul-Haq Qureshi
 * 🇰🇿 Alexander Bublik / 🇺🇸 Reilly Opelka → replaced by Ariel Behar / 🇪🇨 Gonzalo Escobar
 * 🇧🇪 Sander Gillé / 🇧🇪 Joran Vliegen → replaced by 🇦🇷 Máximo González / 🇦🇷 Andrés Molteni
 * Wesley Koolhof / Jean-Julien Rojer → replaced by 🇩🇰 Frederik Nielsen /  Jean-Julien Rojer
 * 🇺🇸 Sebastian Korda / 🇺🇸 Rajeev Ram → replaced by 🇧🇷 Marcelo Demoliner / 🇲🇽 Santiago González
 * 🇩🇪 Kevin Krawietz / 🇦🇺 John Peers → replaced by 🇨🇦 Félix Auger-Aliassime / 🇺🇸 Nicholas Monroe
 * 🇵🇱 Łukasz Kubot / 🇧🇷 Marcelo Melo → replaced by 🇵🇱 Hubert Hurkacz / 🇵🇱 Łukasz Kubot
 * 🇫🇷 Adrian Mannarino / 🇫🇷 Benoît Paire → replaced by Nikoloz Basilashvili / 🇮🇳 Divij Sharan
 * 🇩🇪 Tim Pütz / 🇳🇿 Michael Venus → replaced by 🇦🇺 Luke Saville / 🇦🇺 Jordan Thompson


 * During the tournament
 * 🇩🇪 Yannick Hanfmann / 🇩🇪 Dominik Koepfer