A frustrated Serena Williams looks out onto the court after she lost to Australian Samantha Stosur.

Another day at the French Open and another upset. On Wednesday it was goodbye for Serena Williams.

The top-seeded Williams sister was knocked out of the French Open Wednesday in the quarterfinals (6-2, 6-7 (2), 8-6.) by Australian Samantha Stosur who has played the part of spoiler this week. Stosur knocked out four-time champ Justine Henin, ending Henin's Roland Garros winning streak at 24 matches.

Sports Illustrated senior writer S.L. Price called Stosur's upset the most "impressive women's feat of year," noting that Williams is the number one player in the world, the "best fighter on the tour" and has already won the Australian Open.

"It's not as devastating a loss historically as Roger Federer's was yesterday," Price said. "But it won't be a pleasant night in the Williams family household."