A day after eliminating defending champion Maria Sharapova, Date Krumm won again in her hometown when Daniela Hantuchova was forced to retire with a right shoulder injury while trailing 2-6, 6-0, 4-0.

“Maybe I was lucky because it was my birthday,” Date Krumm said. “Considering I had a tough match yesterday, I felt pretty good today.” Date Krumm, who won the Tokyo tournament in 1995, turned professional in 1989 and retired in 1996, before resuming her career nearly 12 years later. Earlier this year, she became the oldest woman to beat a top 10 player when she defeated Dinara Safina at the French Open.

If she lifts the trophy again in Tokyo, she would become the oldest woman to win a WTA Tour title, replacing Billie Jean King, who won the Birmingham title in 1983 aged 39.

Wozniacki, who had a first-round bye, needed just over an hour to dispatch Arn at Ariake Colosseum for her first win in three appearances in the Tokyo tournament.

“It's a new tournament every year,” said Wozniacki.

“It's a really fast court here, so you need to always be focused.” Wozniacki next faces 16th-seeded Anastasia Pavlyuchenkova of Russia in the third round. Pavlyuchenkova beat Kateryna Bondarenko of Ukraine 6-2, 6-1.

Elsewhere, Russia's Vera Zvonareva overpowered Italy's Sara Errani 6-3, 6-3. The tournament's No. 2 seeded player beat Errani for the third time in three meetings to set up a third-round showdown with Italy's Roberta Vinci, a 6-4, 6-2 winner over Tsvetana Pironkova of Bulgaria.

Zvonareva, this year's finalist at Wimbledon and the US Open, is making her third appearance in the tournament but her previous appearances both resulted in first-round defeats.

Elsewhere, No. 7 Elena Dementieva of Russia trounced Kazakhstan's Yaroslav Shvedova 6-0, 6-1, while No. 8 Victoria Azarenka, prevailed over Lucie Safarova of the Czech Republic 6-1, 6-3.