Second seed Li Na and former champions Venus Williams and Petra Kvitova all progressed to the third round of the women's singles at Wimbledon.
But former semi-finalist and two-time Grand Slam winner Victoria Azarenka of Belarus made an early exit.
The eighth seed, back in action after a foot injury, lost 6-3 3-6 7-5 to Serb Bojana Jovanovski.
Azarenka had beaten Jovanovski when the world number 45 made her Grand Slam debut at Wimbledon four years ago.
Australian Open champion Li, 32, was not at her best but still overcame world number 38 Yvonne Meusburger from Austria 6-2 6-2 in the first game on court two.
Li's next opponent will be Czech Barbora Zahlavova Strycova, who beat 32nd seed Elena Vesnina 6-4 6-2.
The Chinese star is hoping to go better than her three quarter-final appearances at the All England Club.
"It is easy to say, tough to do," she said. "You can pretty easily think about the second week, but for me, if I want to push myself, at least I have to win another match and to come to the second week and then to think about getting further."
Williams, seeded 30, beat Japan's Kurumi Nara 7-6 (7-4) 6-1 and will next face sixth seed Kvitova, who thrashed Germany's Mona Barthel 6-2 6-0 in 55 minutes to reach the last 32.
"I think we both play a similar game, really go for it and she's one of the kind of players that can get really hot and every time she plays me, she plays really well, so I have to be ready for that," admitted the American, who, at 34, is the oldest woman left in the draw.
Kvitova, who had to withdraw from Eastbourne with a hamstring problem, told BBC Sport the injury was holding up well.
"I needed some rest before coming here," she said. "Grass is my favourite surface and Wimbledon gives me lots of nice memories and I played a solid game.
"It will be a tough match against Venus - she is a great champ and likes to play on grass and will be a tough opponent for me."
Fourth seed Agnieszka Radwanska was another straight-sets winner.
The Pole, beaten by Serena Williams in the 2012 final, was a comfortable 6-4 6-0 winner over Australian Casey Dellacqua and will play Michelle Larcher De Brito after the Portuguese defeated Australia's Jarmia Gajdosova 6-3 4-6 6-3.
"The first match on Centre Court is exciting. I was nervous but happy to play good tennis," Radwanska told BBC Sport. "In the second set I was more confident and used to the grass."
|Tracy Austin on Agnieszka Radwanska's win|
|"Radwanska is always a joy to watch - she showed great variety and she is a great thinker and shot-maker on court. She looks very comfortable on grass and she is in a nice section of the draw. It is exciting to see her play this well so early on."|
Slovakia's Dominika Cibulkova, the 10th seed, was forced to dig deep to defeat Belgium's Alison Van Uytvanck, winning 3-6 6-3 8-6, while 12th seed Flavia Pennetta fell to a 4-6 6-7 (4-7) defeat to Lauren Davis of the United States.
In the women's doubles, Serena and sister Venus Williams, seeded eighth, came from behind to overcome Oksana Kalashnikova and Olga Savchuk 5-7 6-1 6-4,.
However, another former singles champion, Martina Hingis, and her partner Vera Zvonareva exited the competition with a 2-6 4-6 loss against fourth seeds Cara Black and Sania Mirza.