AUSTRALIAN OPEN Federer, Ferrero advance, set up showdown

Second-seeded Kim Clijsters aggravated an ankle injury during her match.
MELBOURNE, Australia (AP) -- Roger Federer and Juan Carlos Ferrero had hard-fought victories today to set up a semifinal showdown for the world's top ranking at the Australian Open.
Federer will become No. 1 for the first time if he beats Ferrero, who needs to win the tournament to regain the top spot that he held for eight weeks last year.
"I think my math is good enough to figure that out," Federer said, referring to the complicated points ranking system.
Current No. 1 Andy Roddick was assured of slipping in the rankings after being upset by Marat Safin in the quarterfinals on Tuesday.
Ferrero continued his run for his second Grand Slam by defeating Morocco's Hicham Arazi 6-1, 7-6 (6), 7-6 (5). Second-seeded Federer beat No. 8 David Nalbandian 7-5, 6-4, 5-7, 6-3.
Injury
Second-seeded Kim Clijsters aggravated an ankle injury while beating Anastasia Myskina, leaving her questionable for Thursday's match against Patty Schnyder of Switzerland. Schnyder advanced to her first Grand Slam semifinal with a 7-5 (2), 6-3 victory over American Lisa Raymond.
Also on Thursday's semifinals schedule are top-ranked Justine Henin-Hardenne against 32nd-seeded Fabiola Zuluaga, and defending men's champion Andre Agassi against former top-ranked Safin.
A semifinalist in all four majors last season but still without a Grand Slam title, Clijsters beat Myskina 6-2, 7-6 (9), recovering after a medical timeout in the second set.
Clijsters injured her left ankle at the Hopman Cup and was sidelined for two weeks leading into the Open. She said she would ice it, take painkillers and get it taped before deciding in the morning if she can play.
"I'm going to have a week off after this anyway, so I might as well go for it and give myself a shot," Clijsters said. "But, on the other hand, if I can't walk tomorrow, it's stupid to go out there."
Martina Navratilova, 47, took another step toward her 10th Grand Slam mixed doubles title when she and India's Leander Paes -- the defending champions -- beat Australians Paul Hanley and Trudi Musgrave 6-3, 3-6, 7-6 (7) in the quarterfinals.
Revenge factor
Federer's victory gained him some revenge. Nalbandian beat the 22-year-old Swiss player in the fourth round of the Australian and U.S. Opens last year and had a 5-1 edge in head-to-head meetings.
Federer didn't feel the match lived up to expectations, especially with him committing 55 unforced errors. Still, he did enough to win.
At 5-5 in the first set, Federer faced double break point but ripped four straight aces to hold.
"That was maybe the key of the match," Federer said.
He broke Nalbandian for the set in the next game -- the first set that the Argentine lost in five matches.
It soon became two. With Nalbandian serving at 4-5, Federer went ahead at 0-40. Nalbandian saved two break points before hitting a forehand into the net.
Nalbandian put some pressure on by taking the third set, but Federer broke Nalbandian's next service game to go up 2-0 in the fourth. He rode the advantage to finish off the match with his 20th ace and a serve that Nalbandian hit long.
Good enough
Ferrero was at his best in the key points in outlasting Arazi, even though he was getting tired, his injured groin muscles were aching and Arazi had him sprinting all over the court.
Arazi, ranked 51st, earlier knocked off 25th-seeded Albert Costa and No. 10 Mark Philippoussis. But he came out cold against Ferrero, who won seven straight games spanning the first and second sets, losing only nine points.
In the second set, Arazi came back from 0-2 and fended off two set points with Ferrero serving at 5-4 to break and even the score at 5-5. He led the tiebreaker 6-3 before Ferrero ran off six straight points to take the set.
With Ferrero looking increasingly weary and not moving as well, Arazi broke him for a 4-3 lead in the third set and had a set point on Ferrero's next serve. Ferrero won the game, then broke Arazi to tie the set at 5-5.
"Today was a good test, and I think I passed, I need some rest today and tomorrow," Ferrero said. "I'm very motivated to get (No. 1 spot) again. I'm playing very good, very solid."
Clijsters, a fan favorite as the fiancee of Australian star Lleyton Hewitt, lost the first four games of the second set against Myskina and needed treatment for her left ankle after holding in the fifth.
She won five of the next six games and had two match points on the sixth-seeded Myskina's serve in the 12th before the Russian held to force a tiebreaker. Clijsters had three more match points in the tiebreaker and saved two set points before Myskina's backhand shot drifted wide to close out the match.