NEW YORK, Sep 4 (Xinhua) Li Na became the first Chinese woman to reach the last 16 of the US Open here on Sunday after upsetting last year's runner-up Mary Pierce 4-6, 6-0, 6-0.

"I'm not nervous. I'm excited," said the 24-year-old, who came back to sweep the last 12 games to seal victory after losing the first set to the 13th-seeded French veteran.

Li, having battling injuries this season, blasted 51 winners to just 14 for Pierce though committing 22 unforced errors in the opening set, and turned to make only three errors in a near-perfect second set to turn the match around.

"I was hitting the ball short and my opponent played very good. She served well and hit the ball hard and deep. She didn't give me much of a chance," said Pierce, last year's runner-up at Flushing Meadows.

Li will next play third-seeded Russian Maria Sharapova, who has beaten Li three times without losing a set, twice this season and in the third round of the 2005 Australian Open.