Defending champion Roger Federer survived a five-set thriller to overcome Frenchman Gilles Simon and squeeze into the third round at the Australian Open on Wednesday.

Federer had to pull out all stops to get past the unseeded Simon, winning 6-2, 6-3, 4-6, 4-6, 6-3 in 3hr 13min at the Rod Laver Arena.

The Swiss world number two had cruised to a two-set advantage, but Simon, who had won their only other two encounters, hit back spectacularly to take the contest into a fifth and deciding set.

Federer was relieved to escape with a five-set victory and prevent losing for the first time in the second round at a Grand Slam event since the 2003 French Open.

"Today I got lucky to go through," Federer said.

"He's a great player. Matches against him don't come easy and they always go the distance. Hopefully I won't play him anymore," he laughed.

Federer will next play Belgium's Xavier Malisse in Friday's third round.

Federer's victory equalled Swede Stefan Edberg's record (56-10) for the most Open Era wins at the Australian Open. Federer now has a 56-7 win-loss record at Melbourne Park.

The all-time Grand Slam champion with 16 major titles is bidding to become the second man to win five Australian titles behind six-time winner Roy Emerson.