"It's tough," said, the third seed, who took 67 minutes to see off the world No. 72. "In the beginning, she had huge, big serve, and in grass she was playing more flat balls, so I have to rally every second."Earlier this month, Li became the first Asian player to win a Grand Slam singles title at Roland Garros, but the world No. 4 said she has no extra pressure while coming here.

    "Everybody said congratulations to me here, but that's all about French Open which was over," said the 29-year-old. "I felt no pressure at all. I just began to play another tournament and what I need to do is focusing on my game."Li reached the quarterfinals at Wimbledon last year before she lost to the champion Serena Williams. The two are possible to set up another quarterfinal clash this year, but Li just wanted to say congratulations to the American ace right now.

    "I'm glad to see her back to the tour and I had said it to her at Eastbourne," said Li. "After all, she has been absent for almost a year."Williams, 29, began her title defending journey as the eighth seed and needed one hour and 31 minutes to defeat the world No. 61 Rezai from France 6-3, 3-6 and 6-1.

    The 13-time Grand Slam champion shed tears after the victory. " It's not for winning the match. It was all bout being out there."Williams took her fourth Wimbledon title last year but was forced to stay away from tennis since then after undergoing foot surgery and then developing blood clots in her lung. She finally announced coming back for the grass-court Grand Slam and warmed up at Eastbourne earlier this month.

    Fifth seed Maria Sharapova, the 2004 champion, powered past Russian Anna Chakvetadze 6-2, 6-1 and next faces either British wildcard Laura Robson or Germany's Angelique Kerber.

    Women's world No. 1 Caroline Wozniacki raced into the second round as she routed Spain's Arantxa Parra Santonja 6-2, 6-1, taking just 59 minutes to demolish the world number 105.

    Former world number one Jelena Jankovic, the 15th seed, went out to Spanish left-hander Maria Jose Martinez 5-7, 6-4, 6-3.

    Fourth seeded Belarusian Victoria Azarenka went through when Magdelana Rybarikova of Slovakia retired with a knee injury in the second set.

    Czech eighth seed Petra Kvitova, a semi-finalist in 2010, stormed past American qualifier Alexa Glatch 6-2, 6-2.

    In the men's singles, the seeds also enjoyed a flying start. Six-time men's champion Federer, chasing Pete Sampras's record of seven titles, cruised to a 7-6 (7/2), 6-4, 6-2 win over Mikhail Kukushkin of Kazakhstan. The third seed will next face France's Adrian Mannarino.

    Second seed Djokovic, playing for the first time since Federer ended his 43-match winning run in the French Open semifinals, was equally untroubled needing just 80 minutes to defeat France's Jeremy Chardy 6-4, 6-1, 6-1.(本文由在线英语听力室整理编辑)