Both players held serve throughout the match, and Federer had the early momentum in the first tiebreaker, hitting a couple of blistering forehand winners to go up 3-0. But Nadal won the next five points and clinched the set when the Swiss hit a forehand long.

In the second tiebreaker, Nadal went up 3-1 with a drop volley and Federer sent his return long on the next point.

The Spaniard then set up match point with a crosscourt forehand winner and converted it when Federer hit a forehand long.

“For both of us, these are the first matches of the season. So it is special for us,” Nadal said. “This is the perfect place to start the season here in Abu Dhabi.” Both Federer and Nadal were given byes into the semifinals of the six-player exhibition tournament. Federer beat fifth-ranked Robin Soderling on Friday while Nadal ousted Tomas Berdych.

“I never lost my serve but I still lost the tournament, it's kind of tough,” Federer said. “Rafael and myself must have played so many times and so many times it has come down to a few shots here and there. He is an amazing shot-maker. Me as well but today he got the better of me.” Last month, the two split charity matches with Nadal winning a match in Spain and Federer one in Switzerland.

In tournament play, Nadal has a 14-8 record against Federer. The Swiss won their most recent meeting, a three-set victory in the final the ATP World Tour Finals in London.

In Hua Hin, Thailand, third-ranked Kim Clijsters beat top-ranked Caroline Wozniacki 6-3, 4-6, 12-10 Saturday in an exhibition warm up for the Australian Open.

Clijsters' forehand kept Wozniacki off balance in the first set, but the Dane's game improved in the second following a temporary power failure that forced part of the match to be played in poor light.

The match was part of the 84 World Tennis Invitation in Hua Hin, Thailand, held to celebrate the New Year and honor King Bhumibol Adulyadej, who turns 84 in 2011.

After the match, the players hit 84 autographed tennis balls into the stands.

Clijsters also beat Wozniacki in the final of the season-ending WTA Tour Championships in October and in the 2009 US Open final.