Updated

By Julian Linden

MELBOURNE (Reuters) - China's sporting revolution has been slow in reaching international tennis. More than two million Chinese play the game for fun but only a handful take it seriously enough to make a mark on the professional game.

At the forefront of her nation's batch of leading players is Zheng Jie, who gave the world a glimpse of the changing face of tennis when she made the semi-finals at Wimbledon two years ago.

The diminutive 26-year-old is already through to the quarter-finals of this year's Australian Open and looking to go further but this time, she is not the only Chinese player left in the women's draw.

Her compatriot Li Na is also through to the last eight after defeating Denmark's Caroline Wozniacki 6-4 6-3 Monday.

It was not an upset of major proportions as Li is ranked 17th in the world, but it was still a surprise as Wozniacki made the final of last year's U.S. Open and was seeded fourth at Melbourne Park.

"Yeah, this is good for us, both players in the quarter-finals," Li said, before jokingly revealing the secret behind their success. "Maybe I eat Chinese food."

Wozniacki is a popular figure in Australia but her loss to Li was a victory for the tournament's marketing team who have rebranded the championship as the Grand Slam of Asia/Pacific.

OLYMPIC TRIUMPH

Li's next opponent is Venus Williams, who booked her place in the quarter-finals with a 3-6 6-2 6-1 win over Italian Francesca Schiavone.

That was at the 2008 Beijing Olympics, also in the quarter-finals, with Li emerging triumphant 7-5 7-5.

"It was good experience for me, for my tennis. But I just want to forget (that), because I will play her again."

Williams has never won the Australian Open and time may be running out for her. At 29, she is the oldest woman left in the women's draw and even if she beats Li she could face her younger sister Serena in the semi-finals.

She was well below her best against Schiavone, dropping the opening set then losing her first service game in the second set without winning a point.

But winning a set against the Williams sister is one thing, winning the match is another, and once Venus found her rhythm the contest was over. She remains a serious contender.

"I just realized I was rushing a little too much and I just really needed to take my time," Venus explained.

"It was just the first game. There was a long way to go after the first game still, and I knew that. Everyone knows that."

Serbia's Novak Djokovic sealed his place in the quarter-finals with a 6-1 6-2 7-5 win over Poland's Lukasz, the only unseeded player to make the fourth round of the men's draw.

(Editing by John O'Brien)