By Julian Linden

MELBOURNE (Reuters) - Confident and in form, Nikolay Davydenko can draw some small comfort from facing off against Roger Federer in the quarter-finals of the Australian Open.

But... and it's big but, Davydenko has beaten Federer in their two most recent matches: the semi-finals of last year's ATP World Tour Finals then at the same stage of the tournament in Doha earlier this month.

The Russian cheekily suggested last week that Federer may even be scared of him but he was more diplomatic when asked if those last two wins alone were enough to make him the favorite.

"He's already won the Australian Open a few times. He's number one, I'm number six. Why do I need to be favorite?" said Davydenko, who won his first three matches in straight sets before beating Fernando Verdasco in five.

Federer has also been in great touch this week. He lost the opening set of his first match with Igor Andreev but has not dropped another one since.


His confidence is growing with every match and he shows no signs of losing motivation despite winning the French Open for the first time last year and overtaking Pete Sampras's record of 14 grand slams.

"There's always ways to motivate and challenge you," Federer said.

"I've lived through many more things than I ever thought I would, so I feel very fortunate (but) I'm looking forward to many more years hopefully on tour."

Wednesday's second men's quarter-final between Serbia's Novak Djokovic and Jo-Wilfried Tsonga is a repeat of the 2008 Australian Open final and promising to be a bruising affair.

Djokovic won that match but Tsonga has won of their five meetings since then and the world number three remains wary of the Frenchman.

"He's improved so much, and he's a top 10 player. He has been winning the big matches and knows what it feels like to be on a big stage," Djokovic said.

"It's going to be very difficult for either of us. Jo can beat anyone if he's really on the roll and if he starts hitting the ball well.

"I just to have keep pressuring him and just apply my style of game, not allow him to control the match."

On the women's side, both Williams sisters are heavily favored to emerge from their quarter-finals and meet in the last four. Serena plays Victoria Azarenka of Belarus and Venus faces China's Li Na.

"You have to show your best tennis and be aggressive and try to keep up with her level and be extremely tough," Azarenka said.

"She knows how to play big matches and how to handle herself in tough moments. You just have to be really prepared."


China are already assured of at least one woman in the semi-finals after Zheng Jie beat Maria Kirilenko Tuesday and Li hopes her one and only previous encounter with the American is a positive sign.

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 draw but has lost none of her motivation or confidence.

"I'm ready to go and I feel very well," she said.

"Every match I play, I give a hundred percent. When I lose matches, I really do try to evaluate and bring it back better the next time."

(Editing by John O'Brien)