Nadal had criticised Federer for his unwillingness to speak out on issues affecting the men's game, allowing others to "burn themselves'' as they seek improved conditions for players.

After joining Nadal in the second round of the Australian Open with a win on Monday, Federer said "things are fine'' between the two longtime rivals, although he concedes that they disagree on a way to resolve a list of player grievances which includes the length of the season and the distribution of prize money.

"We can't always agree on everything,'' Federer said. "So far it's always been no problem really. Back in the day he (Nadal) used to say, 'Whatever Roger decides, I'm fine with.'

"Today he's much more grown up. He has a strong opinion himself, which I think is great.''

For his part, Nadal apologized for airing his disagreement with Federer in public although he didn't back down on the views he expressed.