Federer and Djokovic in ATP finals

As usual, Roger Federer is looking to add to one of his many records. And as many expected, Novak Djokovic will be trying to stop him.

The top two players in the world advanced to the championship match at the ATP finals Sunday, each looking beatable early before responding.

Federer, a six-time champion at the season-ending event, advanced by beating U.S. Open champion Andy Murray 7-6 (5), 6-2. The top-ranked Djokovic defeated Juan Martin del Potro 4-6, 6-3, 6-2.

"I knew that if I lose today, it's the end of the season, so I gave everything I had and couldn't be more happy," Federer said on court after the match.

The ATP finals is the last tournament of the season, and Federer will face Djokovic in the final match Monday at the O2 Arena.

Federer found himself in a hole early against Murray, losing his serve in the opening game. Murray, who lost to Federer in the Wimbledon final but beat him in the Olympic final, couldn't maintain the advantage. The 17-time Grand Slam champion broke back to even the score at 4-4, then recovered from a 3-1 deficit in the tiebreaker to win the opening set and take control.

In the second set, Federer lost only two points on serve and broke Murray twice.

"Once he gets ahead, he's incredibly hard to stop," said Murray, who leads Federer 10-9 in head-to-head play. "He tends to play better and better when he gets up."

In the early match, Djokovic started playing his best tennis as soon as he appeared on his way to an early offseason vacation.

Djokovic was broken late in the first set and again early in the second, but he found his stroke and quickly rebounded.

"He's so good," Del Potro said. "Of course, he's the No. 1. In these kinds of matches, they make the difference between them and the rest of the players."