Federer Edges Haas in 5 Sets at Australian Open

"This for me was a good match to win in five," Federer said. "I like to be pushed like this. I'm happy I had a tough one now and I'm still in the tournament."

After Haas' two-set comeback the fifth set was marked by a controversial call that sent Haas into a downward spiral.

"Everything turned around. I was playing fantastic in the first two sets then he played fantastically in the next two," Federer said. "I was really just trying to break his momentum. I knew that all I needed was a break because I was serving pretty well."

No. 5 seed Nikolay Davydenko earned the comeback effort of the day Monday in Melbourne, scrapping back from two sets down against exhausted No. 12 seed Dominik Hrbaty to post a 4-6, 4-6, 6-4, 6-2, 6-3 victory.

"I think nobody believe I can win match today because I was already in third set, was like losing my serve 4-3, he's serving," Davydenko said. "I try like play the same, you know, try to fight. This game I win like 4-all and then try come back, was 5-4. But it was difficult also in the third set. Finish the set because he running good, I try to running also good, and we play a long rally. Was important make no mistake. He make like many mistake in the third set. This is for me good."

Up two sets to love, Hrbaty felt the effects of playing three consecutive five-set matches in his first three rounds.

"I don't feel like I made the mistakes to lose the match. I think he played well to beat me," Hrbaty said. "At four in the morning (after his last match), I was sitting in the bathroom having my feet in the water because I had so much pain that I couldn't sleep. I had a really bad blister on my feet. Then all day I was basically taking care of my feet and went for a swimming pool, had a massage, was worrying if I will be even able to run on the court. In the end, I was really happy the way I played. I mean, I had the pain, but I overcame it and I tried to fight to win the match."

Federer against Davydenko could be a fitness test to see who can recover from their previous five-set match.

Surprise No. 21 seed Nicolas Kiefer stuck to an aggressive game plan in dictating play against Juan Ignacio Chela, defeating the Argentine who had previously ousted Lleyton Hewitt by a 7-6(4), 6-3, 6-3 scoreline.

"It was great that I played aggressive the whole time," Kiefer said. "I didn't care if I made mistakes or not. I mean, I had to play aggressive against this guy. That's what I did. Of course, I had a lot of mistakes, but that's the way how it goes. If you don't make it, you can't win."

Kiefer had 33 errors to Chela's 22, but the tale of the tape was the German's 41 winners to the Argentine's 24.

No. 25 seed Sebastien Grosjean also advanced in an all-French meeting, defeating Paul-Henri Mathieu 7-5, 6-2, 6-2.

Scheduled for Tuesday in Melbourne are (4) Nalbandian vs. Fabrice "The Magician" Santoro, and (7) Ljubicic vs. Marcos "Bombs Over" Baghdatis.