Champion Roger Federer [Images] survived a massive scare at the Australian Open on Saturday, scrambling to a 6-7, 7-6, 5-7, 6-1, 10-8 third-round victory over Serb Janko Tipsarevic.

- Images from Day 6

With the world number one and top seed strangely off-colour, a huge shock looked a real possibility when world number 49 Tipsarevic led by two sets to one but the Swiss came through a tense final set to take his place in the last 16.

"What a great battle. Fair play, he's a nice guy -- pity somebody has to win, wish we could have draws sometimes too," Federer said in a courtside interview.

"This is where you get grey hair early in life. Pity for him, but what a great victory for me."

A sluggish Federer lost the first set, having served for it at 5-3. It was the first set he had dropped at the Australian Open since 2006.

Federer hit back to level the match by cruising through the second set tiebreak, only to lose the third after holding two set points on the Tipsarevic serve in the 10th game.

But Federer, chasing his 13th grand slam title, levelled and in a tense final set, broke in the 17th game and served out to line up a clash with Czech 13th seed Tomas Berdych or Juan Monaco, the 21st seed from Argentina.

Having looked supremely confident in his opening two matches, Federer was expected to breeze past Tipsarevic, who had won only two matches in three visits to the Australian Open until this year.

DOMINANT PLAYER

Federer looked a shadow of the dominant player who has reached 10 successive grand-slam finals and won three of the last four Australian Opens.

It looked like business as usual when the Swiss broke to lead 5-3 in the first set but Tipsarevic broke back and won the tiebreak 7-5 after Federer chose not to hit an easy volley that landed in.

The second set also went to a tiebreak but Federer took it 7-1 to level before forcing two set points in the 10th game of the third.

But, as he did throughout the match, Tipsarevic dug deep on the big points, saving both and stunning the top seed by breaking to take the set 7-5.

Federer had been upset by Tipsarevic's numerous Hawk-Eye challenges in the first three sets but shrugged off his worries by racing through the fourth.

Tipsarevic refused to lie down, however, and stayed on serve until 7-7 in the decider when a backhand pass from Federer forced an error.

The Swiss squandered one match point but an unreturnable serve sealed victory and kept alive his hopes of a third consecutive Australian Open title.

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