London - Rafael Nadal on Friday marked his impending return to tennis after five weeks away with a dose of modesty, as the world number two proclaimed several of his rivals as title favourites at the ATP World Tour Finals.
"Roger (Federer) is winning, Andy (Murray) won three tournaments in Asia, and (Novak) Djokovic must have an incredible confidence for what he did this year. They are the favourites," said Nadal, who last played in a disappointing third-round loss in Shanghai in mid-October.
Nadal will put himself to the test on Sunday night in the eight-man event with an opening Group B match with American Mardy Fish, a year-end event rookie who comes in battling a groin muscle injury.
The Spaniard enters the opener with a 7-1 record against the top American but suffered his only loss last summer to Fish on hardcourt.
The remainder of the group programme for opening day pits Federer against Jo-Wilfried Tsonga in a re-run of last weekend's Paris Masters final won by the Swiss, who comes to London in the best form of any entrant,
World number one Djokovic heads Group A, along with Andy British, Spain's dangerous David Ferrer and Czech Tomas Berdych on board.
Nadal's 2011 season had been modest by his world-class standards, with just three clay trophies won. And Nadal knows that his best chances are not going to come indoors at the O2 arena.
"Playing indoors is more favourable to them," he said of the rest of the field. "You love to talk about favourites, but I'm not. But that's just talk, the point comes when the competition starts."
Nadal cannot help but dream that he can start turning his season around like Federer did with two titles in two weeks and bidding for a record sixth trophy at the elite year-end wrapup.
"Winning a title here would be amazing for me," confessed the king of clay. "But this is the surface where I have worst winning percentage of my career.
"I'm good outdoors, with wind, in varying conditions. Here the conditions are perfect, the ball does not jump so you jump and make it difficult."
Federer, ranked fourth but threatening to overhaul Murray with a solid performance throughout the season wrapup. One slip by Murray and success from the Swiss could put the 16-time Grand Slam champion back on third again.
But the far-sighted Federer - he's already selected his clothing for the season after next, 2013 - is keeping strictly focused on his opening match against Tsonga.
"The top four guys are in good shape," said the uber-fit Federer, 30. "Novak's arm (which forced him from Paris before the quarter-finals) should be okay.
"Rafa could be a touch rusty in the first match, but if he gets through that he's good again. Andy is in great shape already. the Basel (injury) scare is irrelevant. All of the top guys have the potential to win.
And he added: "I'm really looking forward to playing Rafa in the group," he said of the first-time meeting at that stage of round-robin by the elite pair.