US Open champion Samantha Stosur was knocked out of the China Open on Tuesday in another upset at the tournament following shock defeats for the women's Wimbledon and French Open champions. The Australian world number seven lost 5-7, 6-1, 5-7 in the second round to 2005 Beijing champion Maria Kirilenko, following exits for French Open winner Li Na and Wimbledon champion Petra Kvitova. Australian Stosur was beaten in her opener last week in Tokyo -- again by Kirilenko -- as she played her first match since beating Serena Williams in last month's US Open final. Kirilenko broke in the final game in Beijing to claim the victory, with Stosur saving only one of six break points in a match lasting more than two hours. Holder and top seed Caroline Wozniacki and double grand slam finalist Vera Zvonareva, seeded third, restored some order to the day with victories. Wozniacki, who took over the WTA top ranking for the first time in the Chinese capital a year ago, was in merciless form in dispatching Australian Jarmila Gajdosova 6-2, 6-3. Zvonareva, who lost the Wimbledon and US Open finals in 2010, came through a tougher match to beat Czech Klara Zakopalova 6-3, 4-6, 6-2. France's eighth seed Marion Bartoli beat American Christina McHale 6-2, 6-1 and ninth seed Andrea Petkovic of Germany was similarly emphatic as she defeated Carla Suarez Navarro 6-4, 6-4. In the men's draw, top-seed Jo-Wilfried Tsonga, who took the Metz title last month and is bidding to reach the eight-man ATP World Tour Finals, defeated Bulgarian Grigor Dimitrov 7-6 (7/5), 7-5. Tsonga fired nine aces and broke Dimitrov twice in a hard-fought match lasting just under two hours. "It was difficult to play Grigor because he's a really good player," said Tsonga. "For a first round, it was not easy. "I didn't move really well, I didn't hit the ball really good, but I was on the court with my head and I did it. So I'm really happy to go through this one." Third seed Tomas Berdych, plagued by a back injury for the past six weeks, showed his fitness with a win over Jurgen Melzer 7-5, 7-5. Spaniard Marcel Granollers thrashed French fifth seed Gilles Simon 6-3, 6-1 while Russian Mikhail Youzhny dispelled an injury-plagued six weeks to upset fourth seed Nicolas Almagro 6-3, 6-2. China can look forward to having a player in the second round after Zhang Ze beat compatriot Li Zhe 6-1, 6-3.