Former world number one Amelie Mauresmo's troubles continued when she blew four match points on the way to a first-round exit at the Pan Pacific Open on Tuesday.
The Frenchwoman, who has been plagued by injuries this season, was bundled out in a 0-6, 6-1, 7-6 defeat by Slovakia's Dominika Cibulkova in a match riddled with unforced errors.
"I wish I could have that last match point back," Mauresmo told reporters. "On the others she played really good. But it's definitely frustrating to lose when you've had match points."
The former Australian Open and Wimbledon champion refused to contemplate retirement after struggling with injuries and poor form since reaching the summit of the women's game in 2006.
"Last year I was asking myself lots of questions," said the 29-year-old Mauresmo, who has been bothered by rib and thigh trouble throughout 2008.
"But not this year, strangely. Last summer, I had doubts I could compete physically on the same level with the top players, but I found the answer at the end of last year.
"Why do I keep going? Because I still love it. I feel like I still have things to accomplish. I want to evolve a little bit. It's a challenge."
Italy's Flavia Pennetta, who beat Mauresmo in the fourth round of the US Open earlier this month, reached the last 16 in Tokyo with a 6-4, 6-4 win over Israel's Shahar Peer.
Pennetta will face Serbia's world number two Jelena Jankovic in the second round. Jankovic heads a strong field, including six of the world's top 10 players.
Jankovic, fellow Serb Ana Ivanovic and Russians Elena Dementieva and Dinara Safina all received first-round byes as the top four seeds at the $1.34 million event.
Sixth seed Agnieszka Radwanska of Poland beat Japan's Ai Nakamura 6-1, 6-4 to advance to a meeting with France's Marion Bartoli, a 6-2, 6-2 winner over Russian Maria Kirilenko.