Li thrashes Osterloh

Sixth seed Li, who had never previously played on the slick indoor carpet in Tokyo, took advantage of rules allowing on-court coaching at the tournament to cruise into the last 16.

"When I practiced on the court I thought 'How can they play on this?'" Li said afterwards. "I needed to talk to my coach during the match too, but I think I played okay."

The fast-improving Li reached the semi-finals in Sydney before pushing Martina Hingis to three sets in the fourth round of the Australian Open.

"I had a good start in Sydney," Li said. "After Sydney, I told myself I could do it. My ranking has never been top 20 and now I'm 17 I know I can play better."

Meanwhile, fifth seed Ana Ivanovic also advanced to the second round, the Serb overpowering American Shenay Perry 6-4 6-2.

However, Slovakia's Daniela Hantuchova became the first big-name casualty when she beaten 6-4 6-4 by Italian Roberta Vinci.

Eighth seed Hantuchova, once a top-five player, paid the price for an error-strewn performance as she fell to her second first-round defeat in four tournaments in 2007.

In other matches, qualifier Nicole Pratt of Australia beat American Meghann Shaughnessy 6-7 6-1 6-4 while Severine Bremond trounced fellow Frenchwoman Marion Bartoli 6-0 6-2.

World number one Maria Sharapova and four-times champion Hingis head a quality field in Tokyo. The top four seeds received first round byes.