Novak Djokovic stayed perfect at the ATP finals, beating Tomas Berdych 6-2, 7-6 (6) on Friday and qualifying for the semi-finals of the season-ending event.
Djokovic is 3-0 in Group A and will play Sunday for a spot in Monday's final. The other semi-finalist from the group will be decided later on Friday when Andy Murray takes on Jo-Wilfried Tsonga at the O2 Arena.
Murray, who won the U.S. Open and the OIympic gold medal, needs only to take a set against Tsonga to ensure his passage.
After reclaiming the number one ranking at the beginning of the week, Djokovic had little trouble against Berdych. He broke his Czech opponent twice in the first set and once in the second, though he was broken right back on the third occasion to force the tiebreaker.
Berdych then had his opportunities to win the second set, leading 5-1 and 6-3 in the tiebreaker, but he wasted all three of his set points as Djokovic won five straight to close out the match.
"I had some chances in the tiebreak," said Berdych, who was eliminated from the tournament with a 1-2 record.
"If I would be able to make it, try to push him for the third set, then maybe get another chance. But this would be just if. It didn't happen."
Last week, Djokovic lost in the second round of the Paris Masters, and said afterward that he felt down physically.
But against Berdych, the top-ranked Serb was running all over the court, retrieving ball after ball and making his opponent work hard on nearly every point.
"I hope that the best moment is still to come"
Berdych has only beaten Djokovic once in 12 tries, and that came two years ago on grass in the Wimbledon semi-finals. On hard courts, Djokovic is now 10-0 against the hard-hitting Czech.
The ATP finals is the last tournament of the season, and only for the top eight players in the world.
In Group B, six-time champion Roger Federer has already qualified for the semi-finals and will face Juan Martin del Potro in his final group match on Saturday. David Ferrer is also in the group and can still qualify for the semi-finals, but Janko Tipsarevic has been eliminated.
Despite bowing out from the ATP finals, Berdych still has more tennis to play this season. He will lead the Czech Republic against Spain next week in the Davis Cup final.
"It's another week, another event, another big thing. So I will try to get ready for that again," Berdych said.
"I hope that the best moment is still to come.''