Melbourne, Jan 21 (IANS): World No.2 Roger Federer dropped a set but utimately beat Italy's Simone Bolelli 3-6, 6-3, 6-2, 6-2 in the men's singles of the Australian Open tennis tournament here Wednesday.

With this, the 17-time Grand Slam champion advanced to the third round of the competition despite being hampered by a mystery problem on his finger at the Rod Laver Arena.

It was believed the he was stung by a bee which forced the four-time Australian Open champion to receive required medical treatment after losing the first set.

But the right-hander overcame the discomfort to win in two hours and nine minutes smashing 36 winners and compelling his opponent to commit 39 unforced errors.

The Swiss himself was unsure what happened but said he also believed he was stung by a bee.

"I don't know what that thing is. It's the weirdest thing. I don't know. I feel it on the tip of my finger. Just felt really odd starting after the break, and for three, four games, it was the funniest feeling I have. I feel like it's numb and swollen," he explained after winning.

"I knew we couldn't tape it up because then it would be even bigger and more weird. I just said, I hope it doesn't get worse or stay like this."

Federer also acknowledged the performance of Bolelli.

"I wasn't that surprised, to be honest, you know," Federer said about the world No.48’s form.

“Conditions were fast, which made it easier to serve well and harder to return. Maybe the break, I shouldn't be broken, but he was really playing very well from the baseline.

I guess in these conditions sometimes a break can be a set. That's when I was under pressure for a while in the second set, but I'm happy I fought my way out of it,” he opined.