LONDON » Roger Federer made sure Kei Nishikori’s ATP finals ended early. His own beard might be sticking around a bit longer.

Federer made up for his own mistakes in a see-saw match to earn his third straight victory at the season-ending tournament today, beating Nishikori 7-5, 4-6, 6-4 to secure top spot in his group and eliminate the Japanese player.

After the match he faced more questions about his weeklong stubble than about the struggles with his serve that saw him broken five times. Will it stay as long as he keeps winning?

"If it itches too much, I’ll take it off," Federer said. "If my girls can’t stand it, I’ll take it off. If I look in the mirror and I don’t like it, I’ll take it off. Maybe I’ll think of Santa and keep it. It’s around the corner. I don’t know yet."

As for his wife, Mirka, "she’s fine with it."

"I mean, she’s OK, I guess," he added. "I do take decisions by myself sometimes."

Federer broke for a 3-1 lead in all three sets but Nishikori came back each time, taking advantage of some rare mishits by the Swiss star along the way. But Nishikori finally ran out of comebacks as Federer earned his sixth break of the match in the last game, clinching the win with a smash at London’s O2 Arena.

Federer finished the group stage 3-0 while Nishikori was eliminated with a 1-2 record. Top-ranked Novak Djokovic played Tomas Berdych in the late match needing to win just a set to advance.

While Federer had already advanced to the semifinals, there was no let-up in the third set even as Nishikori kept finding ways of getting back into the match.

"It’s just another match, a really important one for me, to move on with a good feeling," Federer said. "There’s (ranking) points on the line and prestige, wanting to beat Kei, winning at the O2. I want to do well here."

Federer had a mini-slump in the first set as Nishikori broke twice to take a 4-3 lead but earned a second break right back after the Japanese player missed two straight forehands. Nishikori had a chance to force a tiebreaker at 6-5 but Federer saved a game point with a backhand passing shot after one of the best exchanges of the match. Nishikori then hit two shots into the net to hand Federer the set.

The Swiss star, who beat both Berdych and Djokovic in straight sets, looked headed for another routine victory when he hit a backhand return winner to go 3-1 up in the second. But Nishikori broke back and Federer then handed him another game point when he badly mishit an easy forehand volley at the net at 4-4.

"I don’t know why but I returned really well," Nishikori said. "That’s why (I was) able to break a lot of times."

Federer then dug himself out of a 0-40 hole in the third game of the decider before breaking for another 3-1 lead. He wasted that one as well as Nishikori pulled level at 4-4, but it was the Japanese player who made the final key mistake.

Serving to stay in the match, Nishikori double-faulted at 40-30 and then missed a forehand long to hand Federer match point. Federer finished emphatically, jumping up to hammer home a forehand smash.