The top-seeded Russian struggled with her serve in the wind at the French Open, hitting 17 double-faults and barely managing to defeat 103rd-ranked Evgeniya Rodina 6-1, 3-6, 8-6 Wednesday in the first round.
Fifth-seeded Serena Williams, the only former champion in the women's field, won the final four games to defeat Mathilde Johansson of France 6-2, 7-5 and advance to the third round.
Rafael Nadal had an easier time in his opener, improving to 22-0 for his career at Roland Garros by defeating Thomaz Bellucci 7-5, 6-3, 6-1 in a rain-interrupted match.
After rain suspended play Tuesday with the score at 1-1, Nadal was broken twice in the first set Wednesday, including while serving for the set at 5-3 before eventually winning.
"In two days I only practiced 20 minutes," said Nadal, adding the windy conditions were tough. "Difficult to go to the court and have a good rhythm. And first match, always you are nervous."
Nadal, seeded No. 2 behind Roger Federer, is trying to become the first man since Bjorn Borg in 1978-81 to win the clay-court Grand Slam tournament four years in a row. His next opponent is another qualifier, Nicolas Devilder of France.
Third-seeded Novak Djokovic moved into the third round by beating Miguel Angel Lopez Jaen of Spain 6-1, 6-1, 6-3.
"It's always good to have an easy match," the Australian Open champion said.
Sharapova landed only 64 percent of her first serves in the match on center court, where she is trying to complete a career Grand Slam at the clay-court major.
"I was very close to losing this match," Sharapova said. "Not many things were working for me today after the first set."
The 19-year-old Rodina came within two points of winning at 5-4 in the third set, but Sharapova won the next two with strong serves to hold. At 6-6, Sharapova regained control by breaking serve for the first time in the final set, returning a second serve with a big forehand that caught Rodina flat-footed.
Then, serving for the match, Sharapova double-faulted one final time, but took the next three points to end it.
In the fifth game of the second set, Sharapova double-faulted three times in a row. After the third, she put her hands on her hips and stared blankly.
"I had problems in every department of my game today, so I'll have to improve on every aspect of those things," Sharapova said.
Although Sharapova was having trouble landing her serves, the three-time Grand Slam champion was more consistent with her groundstrokes, often playing long rallies before hitting a winner or waiting for Rodina to make a mistake.
"I just hung in there. It was far from my best tennis today," Sharapova said. "But at the end of the day you try to learn from your mistakes."
Sharapova didn't directly blame the windy conditions for her poor play.
"Apart from eating and breathing the sand, it was great," she said.
Sharapova dominated the first set, losing only her first service game. In one stretch, she won 10 of 11 points to take a 4-1 lead.
But the Russian then double-faulted three times in the following game before she held.
Rodina broke Sharapova in the first game of the second set, and then held for the first time to take a 2-0 lead. She held the rest of the way and broke Sharapova again in the final game of the set.
Rodina was playing in her first Grand Slam tournament. She lost in the first qualifying round at the Australian Open this year.
"This is life," Rodina said with a laugh. "I could have won, but it's OK."
Rain delays over the first three days of the tournament gave way to strong wind on Day 4, when organizers hoped to cut through a huge backlog of matches.
Second-seeded Ana Ivanovic advanced to the third round. Last year's French Open finalist easily beat Lucie Safarova 6-1, 6-2.
No. 14 Agnieszka Radwanska and No. 30 Caroline Wozniacki also reached the third round. No. 9 Marion Bartoli, who reached last year's Wimbledon final, was upset by Casey Dellacqua 6-7 (4), 6-3, 6-2 in the first round. But No. 7 Elena Dementieva, No 6. Anna Chakvetadze, No. 11 Vera Zvonareva and No. 18 Francesca Schiavone all advanced to the second round.
In the men's draw, No. 25 Lleyton Hewitt defeated Nicolas Mahut of France 6-4, 6-2, 6-4 and No. 5 David Ferrer beat Steve Darcis 6-3, 6-4, 6-3. No. 15 Mikhail Youzhny, No. 21 Radek Stepanek, No. 26 Jarkko Nieminen and No. 30 Dmitry Tursunov also advanced, while No. 20 Ivo Karlovic lost.
Juan Carlos Ferrero, the 2003 French Open champion, retired with leg pains while leading Marcos Daniel of Brazil 7-6 (5), 2-2.
"I've suffered this pain for quite a while," the 23rd-seeded Ferrero said. "I thought I had recovered for this tournament. ... It didn't hurt, but then the pain, I started feeling the pain again."