French Open 2017: Venus Williams loses to Timea Bacsinszky to leave women's draw wide open

The 30th seed beat the 10th seed 5-7 6-2 6-1 in a topsy-turvy encounter on Philippe-Chatrier.

Williams, who reached the final of the Australian Open, was the last woman in the draw who had previously won a Grand Slam.

Bacsinszky goes through to face 15th seed Kristina Mladenovic, who earlier on Sunday beat defending champion Garbine Muguruza.

It was the second year running that Williams, seeded 10th and competing in her 20th French Open, lost to the Swiss in the Roland Garros fourth round even though she fought back from 5-1 down to rattle off six straight games to win the first set.

"She just played well. She just came out with great tennis a lot of the time. The risk was rewarded for her," Williams said. "I feel I played well today but I did not quite figure out the solution in time."

Williams, whose sister Serena is not playing in the tournament as she is expecting her first child, ran out of steam in the last two sets.

The 27-year-old Bacsinszky, who had wasted two set points in the first set, frustrated the American by playing a string of drop shots and won the next two sets with ease. The Swiss clinched the match with a delectable drop shot.

"The first set I had a big lead but I started making catastrophic errors," Bacsinszky said.

"I then threw some cold water on my face and told myself not to finish the Sunday like that. So I came back and played a more versatile game."