Until last night Roger Federer, the No 1 seed at the Australian Open, had not dropped a set and appeared unassailable. Then he met Tommy Haas, unseeded but dangerous, in the fourth round. He emerged unscathed, but only just, extracting a 6-4, 6-0, 3-6, 4-6, 6-2 victory.
Federer, the 2004 champion, said: "I was playing fantastic for the first two sets, then he played fantastic for three and four. After that it was tough to break the momentum. It was really hard work. I like to be pushed like this."
Haas, who reached No 8 in the world in 2001 but whose career has since been plagued by injury, said: "I think I pushed him as much as I could today."
Federer will meet Nikolai Davydenko, the No 5 seed, in the quarter-finals tomorrow, after the Russian beat Slovakia's Dominik Hrbaty, also in five sets.
Federer's Swiss compatriot Martina Hingis also survived a testing fourth-round match with Samantha Stosur, the last local player in the draw.
Playing her first Grand Slam since the 2002 US Open, Hingis held her nerve in the second set to win 6-1, 7-6 and reach the last eight without dropping a set.
Hingis, a wild-card entry, is the only unseeded player left in a women's draw. She will play the second seed Kim Clijsters tomorrow after the Belgian, who has been troubled by hip and back problems, progressed with a 7-6, 6-4 win over Italy's Francesca Schiavone.
"My injury's not gone. The pain is gone because of the tablets I'm taking," Clijsters said. "So that's a good sign that I can be out there and play without feeling the pain. But I know that once I get home there's going to be some work to do."
The third seed Amélie Mauresmo sounded a warning that this could finally be her year by hammering the Czech teenager Nicole Vaidisova 6-1, 6-1 in just 52 minutes. Mauresmo, yet to win a Grand Slam singles title, will meet Patty Schnyder after the Swiss seventh seed overwhelmed former French Open champion Anastasia Myskina 6-2 6-1.
On the men's side, the matches all went to script, with Davydenko, Nicolas Kiefer of Germany and Sébastien Grosjean of France all winning. Davydenko, the fifth seed, came from behindto beat Hrbaty 4-6, 4-6, 6-4, 6-2, 6-3, ending the Slovakian's incredible run in the tournament.
Australian Open results
Fourth round: R FEDERER (Swit) bt T HAAS (Ger) 6-4 6-0 3-6 4-6 6-2; N DAVYDENKO (Rus) bt D HRBATY (Slovak) 4-6 4-6 6-4 6-2 6-3; N KIEFER (Ger) bt J I Chela (Arg) 7-6 6-3 6-3; S GROSJEAN (Fr) bt P-H Mathieu (Fr) 7-5 6-2 6-2.
Fourth round: P SCHNYDER (Swit) bt A MYSKINA (Rus) 6-2 6-1; A MAURESMO (Fr) bt N VAIDISOVA (Cz Rep) 6-1 6-1; M Hingis (Swit) bt S Stosur (Aus) 6-1 7-6; K CLIJSTERS (Bel) bt F SCHIAVONE (It) 7-6 6-4.
Third round: J Hernych (Cz Rep) and I Karlovic (Croa) bt P Baccanello and R Smeets (Aus) 7-6 5-7 7-6; S ASPELIN (Swe) and T PERRY (Aus) bt J KNOWLE and J MELZER (Aut) 6-2 6-4; M Fyrstenberg and M Matkowski (Pol) bt F SANTORO (Fr) and N ZIMONJIC (Serb-M) 7-5 7-5; M DAMM (Cz Rep) and L PAES (Ind) bt M BHUPATHI (Ind) and W MOODIE (SA) 3-6 6-3 6-2.
Third round: G DULKO (Arg) and M KIRILENKO (Rus) bt D HANTUCHOVA (Slovak) and A SUGIYAMA (Japan) 6-1 6-1; ZI YAN and JIE ZHENG (Ch) bt E DEMENTIEVA (Rus) and F PENNETTA (It) 6-1 6-2; V RUANO PASCUAL (Sp) and P SUAREZ (Arg) bt S KUZNETSOVA (Rus) and A MAURESMO (Fr) w/o; C BLACK (Zim) and R STUBBS (Aus) bt M Krajicek (Neth) and A Szavay (Hun) 6-4 6-1.
First round: A Ram (Isr) and L Huber (SA) bt N ZIMONJIC (Serb-M) and K SREBOTNIK (Sloven) 7-5 7-6; B BRYAN (US) and V ZVONAREVA (Rus) bt S Huss (Aus) and S Mirza (Ind) 6-3 6-3; J BJORKMAN (Swe) and L RAYMOND (US) bt J Melzer (Aut) and A Myskina (Rus) 6-2 6-2. Second round: M Bryan and C Morariu (US) bt G Monfils and A Cornet (Fr) 6-2 6-3.
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