Top seed Monica Seles grunted and grimaced her way to a 7-5 5-7 6-1 victory over Ai Sugiyama at the Pan Pacific Open.
The former world number one, who sprained her left ankle during her Australian Open defeat to Czech Klara Koukalova, squandered four match points with Sugiyama serving at 4-5 in the second set.
But Seles, her movement clearly restricted, broke twice before sealing victory on her sixth match point when Sugiyama swatted a forehand return wide.
“Every once in a while I feel pain and obviously I’m not as ready as I would have wanted,” said the 29-year-old Seles, a winner of nine grand slam singles titles.
“It’s been a tough two weeks after the Australian Open. After not practising much, I was not that comfortable with my game. I just tried to hang in and fight for every point.”
Organisers of the $1.3m event are hoping that Seles does not suffer any relapse this week after Martina Hingis, Jennifer Capriati and Anna Kournikova all pulled out with injuries before the start of the tournament.
Meanwhile, fourth seed Chanda Rubin opened with a 6-4 6-0 drubbing of Slovenian Katarina Srebotnik in her first match in Tokyo since 2000.
Former champion Iva Majoli, a first-round loser in Melbourne, quickly got her game back on track with a convincing 6-3 6-3 victory over American Alexandra Stevenson.
In other matches, doubles specialist Lisa Raymond beat Argentine Paola Suarez 6-1 4-6 7-5 while Indonesian Angelique Widjaja defeated wildcard Jeon Mi-ra of South Korea 6-3 6-3 in an all-Asian clash.