Serena Williams was forced to pull out ahead of her second-round match against Tsvetana Pironkova.
The 23-time grand slam champion came into the tournament nursing an Achilles injury she picked up during her semi-final defeat at the US Open earlier this month.
Meanwhile, 12-time champion Rafael Nadal laid down a marker with a thumping 6-1 6-0 6-3 win over Mackenzie McDonald.
Here, the PA news agency looks back at day four at the French Open.
Picture of the day
Stat(s) of the day
Smash of the day
Yulia Putintseva’s win over Nadia Podoroska wasn’t all plain sailing.
Quote of the day
Match of the day
Sixth seed Alexander Zverev is no stranger to a five-set marathon and he came through another to squeeze past Frenchman Pierre-Hugues Herbert.
The German, runner up to Dominic Thiem at the US Open earlier this month, won 2-6 6-4 7-6 (5) 4-6 6-4.
Women: Serena Williams (6)
Men: John Isner (21), Benoit Paire (23)
— Roland-Garros (@rolandgarros) September 30, 2020
Novak Djokovic and Stephanos Tsitsipas headline on Chatrier while former champion Garbine Muguruza faces Kristyna Pliskova on Suzanne Lenglen.