World number one Maria Sharapova struggled with her serve at a wind-blown Wimbledon on Friday before overcoming Taiwan's Hsieh Su-wei 6-1 6-4 to reach the fourth round.
The top seed dominated the first set with a free-flowing game that oozed confidence as Hsieh, the daughter of a Taiwanese locksmith, just could not find the key to the Russian's armoury of powerful groundstrokes.
But Sharapova, who completed her career grand slam this month with victory in the French Open, then let her concentration slip.
Twice she lost her serve, clearly thrown by the swirling wind and delivered a string of double-faults much to her own fury.
Hsieh led 4-2 but could not maintain the pressure against Sharapova who clawed her way back. Hsieh saved two match points but lost the third when she sent a backhand wide.
The elegant Russian, who first won Wimbledon in 2004 at the age of 17, will have to sharpen her game against her next opponent, last year's semi-finalist Sabine Lisicki of Germany.
"That's a tough one," Sharapova said. "She did extremely well last year. She is a very good player on grass and I look forward to it."