Defending champion Maria Sharapova served 13 double faults against fellow Russian Vera Zvonareva, losing 4-6, 7-5, 6-1 and costing her the No. 1 ranking at the Pacific Life Open on Tuesday.

Sharapova was beaten in the fourth round and needed to reach the semifinals to remain No. 1. She will be supplanted by Justine Henin when the rankings are updated on Monday. Henin, who was not at this tournament, won two recent events in the Middle East.

Sharapova served for the match at 6-4, 5-4 but won only a point.

“After that I just deflated a little bit,” Sharapova said.

Zvonareva won the last four games of the second set, and the first four of the third set. Sharapova broke Zvonareva to end the streak but lost her next service game by delivering two double faults, bouncing her second serve into the net on one of them.

Moments later, Zvonareva clinched a berth in the quarterfinals with her third win against Sharapova in seven matches.

Asked about the problems with her serves, Sharapova said, “Yeah, there were a lot of wrong things going on today. That was just one of them, especially in the third set. But it was more of a snowball effect than anything else.”

Sharapova was under pressure in her third event this year. After reaching the final in Melbourne, she strained a hamstring in the semifinals of the Tokyo Indoors event more than a month ago.