Defending champion Maria Sharapova and fourth seed Petra Kvitova were sent packing from the French Open at the fourth-round stage on Monday, but top seed Serena Williams survived a scare to seal her quarter-final place.

Sharapova lost 7-6 (7-3) 6-4 to Lucie Safarova, the Czech 13th seed who will now meet Garbine Muguruza of Spain in the last eight.

Wimbledon champion Kvitova lost 2-6 6-0 6-3 in three sets to Swiss 23rd seed Timea Bacsinszky.

Williams, meanwhile, lost the first set against compatriot Sloane Stephens on Court Philippe Chatrier but came back to win 1-6 7-5 6-3 and set up a quarter-final with Italy’s former finalist Sara Errani.

Sharapova, who also won the claycourt grand slam event in 2012 and was the beaten finalist in 2013, had been forced to wait until Monday morning for her clash with Safarova, which had been postponed on Sunday due to rain in the French capital.

But on a bright Paris morning the Russian second seed, who was looking to become the first woman to successfully defend the French Open title since Justine Henin in 2007, was punished for an erratic display from beginning to end.

“I had a few small openings but I wasn’t able to keep up my level. She was more consistent and aggressive, created the angles and that was the difference,” said Sharapova, who had been battling a heavy cold all week.

“It was a tough day at the office.”

Williams kept alive her hopes of winning a third French Open and a 20th grand slam crown, but only after another sluggish opening to her match.

Just as against Anna-Lena Friedsam and Victoria Azarenka in the previous two rounds, Williams lost the first set, Stephens breaking three times to take it 6-1.

The unseeded Stephens beat Venus Williams in the first round and was looking to become the fourth player to defeat both sisters at the same grand slam after Martina Hingis, Henin and, most recently, Kim Clijsters at the 2009 US Open.

Serena found herself serving to stay in the match at 4-5 in the second set but won the game and went on to take the set 7-5 before claiming the decider to secure her passage after exactly two hours on court.

“I feel like I’m living on the edge but I’ve got to get off the edge. I dont like to take chances,” said Serena after winning three straight matches from a set down at a major for the first time since the 1999 US Open – a tournament which gave her the first grand slam title of her career.

“I’m not really happy about my performance. To go three sets back to back to back is verging on unprofessionalism for me.”

Errani, the Italian 17th seed who was the runner-up in 2012, lies in wait after she beat unseeded German Julia Goerges 6-2 6-2.

Spanish 21st seed Muguruza won through to the quarter-finals for the second year running by beating Italian Flavia Pennetta 6-3 6-4.

Twelve months ago the Venezuelan-born Muguruza was knocked out in three sets by Sharapova, having defeated Serena in the second round.

Belgian Alison Van Uytvanck will meet Bacsinszky after winning through to a grand slam quarter-final for the first time by beating a fellow unseeded player, Romanian Andreea Mitu 6-1 6-3.

The 21-year-old, ranked 93 in the world, becomes the first Belgian to reach the quarters at Roland Garros since Henin in 2007.

The other quarter-final pairs seventh seed Ana Ivanovic with Ukraine’s 19th seed Elina Svitolina on Tuesday.