Roger Federer and Juan Carlos Ferrero, dueling each other for the top ranking, had hard-fought victories yesterday to set up a semifinal showdown at the Australian Open in Melbourne.

　　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. Current No. 1 Andy Roddick was assured of slipping in the rankings by losing in the quarterfinals.

　　Second-seeded Kim Clijsters aggravated an ankle injury while beating Anastasia Myskina, leaving her questionable for today'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 today'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 Marat Safin.

　　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.

　　The second-seeded Federer's 7-5, 6-4, 5-7, 6-3 victory over No. 8 David Nalbandian gained him some revenge. Nalbandian beat the 22-year-old Swiss player in the fourth round of the Australian and US Opens last year and had a 5-1 edge in head-to-head meetings.

　　At 5-5 in the first set, Federer faced double break point but ripped four straight aces to hold. He broke Nalbandian for the set in the next game when the Argentine hit a forehand into the net. It was the first set that Nalbandian lost in five matches at Melbourne Park.

　　Nalbandian got his first break in the first game of the second set, but Federer tied it up at 2-2 on a controversial line call. Serving at 30-40, Nalbandian thought he hit the line to take the score to deuce, but the ball was called just out for a break.

　　At 3-3, they swapped breaks again. With Nalbandian serving at 4-5, Federer had triple break point at 0-40. Nalbandian saved two before hitting a forehand into the net to end the set.

　　With Federer serving at 5-5 in the third, Nalbandian broke on a jumping backhand crosscourt winner, then held for the set, after trailing 0-30, when Federer hit a forehand long.

　　But Federer broke Nalbandian's next service game to go up 2-0 in the fourth set and rode the advantage to finish off the match with his 20th ace and a serve that Nalbandian hit long.

　　With the motivation of winning his second Grand Slam and regaining the No. 1 ranking, Ferrero was at his best in the key points in outlasting Morocco's Hicham Arazi 6-1, 7-6 (6), 7-6 (5) even though he was getting tired, his injured groin muscles were aching and Arazi had him sprinting all over the court.

　　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.

　　A semifinalist in all four majors last season but still without a Grand Slam title, Clijsters beat Myskina 6-2, 7-6 (9). A fan favorite as the fiancee of Australian star Lleyton Hewitt, Clijsters lost the first four games of the second set 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.