Maria Sharapova defeated Tamarine Tanasugarn of Thailand 6-2, 7-5 in the second round of the rain-hit Pan Pacific Open on Monday.
After taking the first set in 30 minutes behind a blistering forehand, the second-seeded Russian quickly went up 3-0 in the second set before faltering.
Tanasugarn suddenly came to life, breaking Sharapova in the fourth game, and winning five of the next seven games to make it 5-5.
Sharapova dug deep in the 11th game, however, breaking again and then closing out the match with an ace to finish the contest in 1 hour, 31 minutes at a covered Ariake Colosseum.
"I served really well today," Sharapova said. "It was important for me to serve well because she reads the ball really well.
"I had a bit of letdown in the second set. She started playing really well. I was glad I was able to come back and win it in two sets."
Playing in her first tournament in Japan since the March 11 earthquake and tsunami, Sharapova said she and her fellow competitors were happy to support the event.
"The commitment the players have shown is incredible," she said. "With nearly a full draw, I think the players have shown their dedication (to this event)."
The annual WTA Tour tournament is normally an outdoor event, but rain in the late morning forced the closure of the roof over the main court and suspension of play on the outdoor courts.
Also, seventh-seeded Marion Bartoli of France defeated Ayumi Morita of Japan 6-3, 0-6, 6-3 and eighth-seeded Jelena Jankovic of Serbia beat Barbora Zahlavova Strycova of the Czech Republic 6-4, 6-2.
Bartoli prevailed in a baseline battle despite a second-set whitewash. She overpowered Morita with a strong backhand in a final set that saw breaks of serve in the first three games.
Morita committed several unforced errors in the third set, ultimately leading to her defeat. Serving to stay in the match, Morita staved off four match points before finally succumbing.
Qualifier Mandy Minella of Luxembourg rallied to beat Japanese veteran Kimiko Date-Krumm 1-6, 6-3, 6-3 and 12th-seeded Ana Ivanovic of Serbia defeated qualifier Anastasia Rodionova of Australia 6-4, 6-0.
Defending champion Caroline Wozniacki of Denmark, the top-seeded player in the $2,000,000 tournament, has a first-round bye and will meet the winner of the match between Rebecca Marino of Canada and Jarmila Gajdosova of Australia on Tuesday.
US Open champion Samantha Stosur of Australia also has a first-round bye. She will take on either Maria Kirilenko of Russia or Erika Sema of Japan on Tuesday.