Seventh seed Serena Williams survived some erratic moments to beat Spain's Lourdes Dominguez Lino 7-5 6-0 in the first round of Wimbledon on Monday.
Williams, a double winner of the grasscourt grand slam, appeared to struggle with her concentration in a match suspended for about 90 minutes because of rain at 3-3 in the first set.
Out of a 10, I was probably at a two, maybe," she told a news conference.
"I hit six double faults, which is more than I hit in a tournament normally. I never double fault, so that was strange, very weird out there," said Williams, who added that she was suffering from a tight hamstring.
"I'm hoping and praying it will get better in time. It's gotten better since I've been getting treatment on it.
"I did feel a little limited but I think if things had been tougher, I would have fought through it. I just would have kept going and fighting harder and harder for sure," the eight-times grand slam winner said.
Watched by her sister Venus, with whom she is entered in the doubles, Williams was broken shortly after play resumed, putting the ball out to give Dominguez Lino a 5-4 lead and the chance to serve for the set.
That gave Williams a jolt and she won the next three games to take the set. With the crowd behind her, the 25-year-old American powered her way through the second set in 24 minutes, despite making 20 unforced errors in the match.
Williams faces Australian Alicia Molik in the second round.