Novak Djokovic stayed perfect at the ATP finals, beating Tomas Berdych 6-2, 7-6 (6) and qualifying for the semi-finals of the season-ending event.
Djokovic lost in the second round of the Paris Masters last week, and said afterward that he felt down physically. But against Berdych, the top-ranked Serb ran all over the court, retrieving ball after ball and making his opponent work hard on nearly every point.
"If you are winning matches, I mean, obviously you feel better," Djokovic said. "But still, I mean, the fact is that it being the last tournament of the year here in London for most of the players, it is a challenge finding that last drop of energy, physical, mental, to find their best game and go as far as they can."
Djokovic is 3-0 in Group A and will play Sunday for a spot in Monday's final.
After reclaiming the No 1 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."
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.
Besides playing tennis and winning tournaments, Djokovic has also had his father's health on his mind. On Friday, the top-ranked Serb said his father was getting better but didn't give any detail as to what the problem is.
"Well, every win means a lot for my family and me," Djokovic said. "But there are more important things in life, and that's health. I guess that's the priority now."
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."