PARIS– A day after the men’s world number 1 was sent packing from Roland Garros, the women’s top-seed followed suit.Samantha Stosur recorded her second upset in three days on Wednesday, defeating Serena Williams 6-2, 6-7 (2), 8-6 to advance to the semifinals of the French Open.It may not have been as big a surprise as Roger Federer’s exit in the last eight on Tuesday, but considering the Australian had knocked out four-time champion Justine Henin just two days ago and also saved a match point on her way to victory on Wednesday, it is certainly no less an achievement than Robin Soderling’s win over the top-ranked Swiss.Stosur played some brilliant tennis, winning 17 consecutive points during one stretch. The 26-year-old, seeded No. 7, served for the match in the second set, but Williams mounted one of her patented comebacks, and as the tension built in an error-filled third set, she came within a single point in the 10th game for the victory.However, her forehand sailed an inch long and Stosur then regained her early form. She hit consecutive cross-court winners to break for a 7-6 lead, then served out the victory, hitting service winners on the final three points.“I didn’t want to let her try and dictate the points early on,” Stosur said. “I just kind of hung in there in the third set, and I was behind the whole time serving second. Just tried to hang in and wait for another opportunity. Then I got one at 6-all, and thankfully I took it.” Stosur, a semifinalist for the second year in a row, will play Thursday against No. 4 Jelena Jankovic, who beat unseeded Yaroslava Shvedova 7-5, 6-4. Jankovic, who rallied three times from a service break down in the second set, also reached the semifinals in 2007 and 2008, only to lose each time.Also Wednesday, Rafael Nadal continued his march towards a fifth French Open title, beating fellow Spaniard Nicolas Almagro 7-6 (2), 7-6 (3), 6-4.Nadal, who has yet to drop a set in the tournament, will face No. 22 seed Jurgen Melzer in Friday’s semis after the Austrian came back from two sets down to stun third seed Novak Djokovic.The Serbian seemed to be cruising after two sets, but Melzer, who had never past the third round of a Grand Slam tournament until last week, stormed back and claimed a 3-6, 2-6, 6-2, 7-6 (3), 6-4 victory.With sunshine returning at Roland Garros, Stosur wore her distinctive sunglasses and embraced the role of underdog.In contrast, Williams often seemed hesitant, indecisive and on the defensive, pinned deep by Stosur’s big forehand and slice backhands. Williams hit one backhand that barely reached the bottom of the net, took an awkward swing at an overhead and flubbed a forehand putaway in the forecourt.Williams hit 13 aces but also nine double-faults and committed 46 unforced errors to 24 for Stosur.Williams was serving at 2-3, 30-all in the first set when her gamebegan to unravel. She committed unforced errors on the next two pointsto lose serve, and Stosur won the next three games at love, a shockingstreak against the world’s No. 1 player.Stosur looked nervous for the first time serving for the match at 5-3in the second set. She double-faulted for the first time, hit the netpost with a forehand and fell down chasing a ball on break point.Several tentative shots cost her in the tiebreaker, and the ever-resilient Williams evened the match.However, Stosur hit a flurry of winners at the finish that had thecenter court crowd roaring. Perhaps the win was not thatsurprising: Stosur has the most wins on clay this year on the women’stour, with a record of 19-2. A two-time Grand Slam champion in women’s doubles, she’s ranked a career-best No. 7.AP contributed to this report.