Roger Federer's [Images] seemingly unstoppable march towards another Australian Open [Images] title meets its biggest hurdle yet when he faces Marat Safin [Images] in the semi-finals on Thursday.

Federer is one of the hottest favourites in history to win the opening Grand Slam of the season but the Swiss master is wary about Safin even though the odds are heavily stacked in his favour.

Federer beat Safin in last year's Australian Open final and has won six of their previous seven clashes, including their epic battle in the semi-finals of last year's Masters Cup when he won a second-set tiebreak 20-18.

The world number one has also won his past 24 matches against players ranked in the top 10 and has yet to drop a set in the tournament after demolishing Andre Agassi [Images] in the quarter-finals. He insists he is taking nothing for granted against the big-serving Russian, however.

"I'm really looking forward to the contest with Safin," Federer said.

"I have the feeling he's playing good again and he had a great finish last year, good start again. So it's going to be a really hard match."

Safin was too exhausted to mount any real challenge to Federer in last year's final after surviving a series of five set matches but has dropped only two sets so far this year.

"There are no more easy matches," Safin said. "Everybody knows basically how to play against Roger but no-one can manage to get closer than three sets."

WIMBLEDON [Images] REVENGE

Serena Williams [Images] will be looking to avenge her defeat by Maria Sharapova [Images] in last year's Wimbledon final when they meet in the first of Thursday's two women's semi-finals.

The Russian teenager also beat Williams in the final of the season-ending tour championship and the former world number one is expecting another tight encounter.

"She's playing really good. I think she's a really mentally tough character out there."

Both Sharapova and Williams began the Australian Open slowly but have hit form at the perfect time. Sharapova came from a set down to beat US Open [Images] champion Svetlana Kuznetsova [Images] in the quarter-finals while Williams thrashed second seed Amelie Mauresmo [Images] 6-2, 6-2.

Williams has not won a Grand Slam title since her victory in Melbourne [Images] two years ago but scoffed at suggestions she was a spent force in the game.

"I don't have to win this tournament to prove anything," she said. "I know that I'm out here and I know that I'm one of the best players out here."

World number one Lindsay Davenport [Images] plays Nathalie Dechy [Images] in the second semi-final after she survived a scare from Alicia Molik [Images] to win 6-4, 4-6, 9-7.

Davenport has not won a Grand Slam title for five years but is a hot favourite at least to make the final.

"I played her in Sydney [Images] last week and we had actually a great match, close two sets. I think she's a good player," Davenport said.

"I have not really thought about it much, but I think she's, you know, has a great opportunity. First semi-final, she has nothing to lose tomorrow."

Dechy has lost each of her five previous matches against Davenport but said she was playing at her best now.

"She's such a great lady and such a great champion that I'm really happy to play against her," Dechy said.

"I'm playing much, much better than two weeks ago. I haven't thought about it too much yet, but I will go for it."

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