Roger Federer, who defeated world No. 1 Novak Djokovic in straight sets during the round-robin stage of the ATP World Tour Finals, says that while the Serb was not at his best, his own play had a lot to do with that.

“He wasn't as good as in the first set,” said Federer after his 7-5, 6-2 win. “But I feel, honestly, with the way he's played this season, you still have to put him away. It's not an easy thing to do. It's not like he played terrible. I know he can play better. Why did he play that way? I'd like to give myself credit for that, quite honestly.”

For his part, Djokovic was not pleased with his performance, saying, “I handed him the match, especially in the second set."

Djokovic had gone unbeaten since winning his 10th Grand Slam singles title at the U.S. Open. His previous loss came to Federer in the Cincinnati final. Djokovic then compiled a 23-match winning streak, winning titles at the U.S. Open (where he beat Federer in the final), Beijing, Shanghai, and Paris. Head to head, Federer has 22 victories and Djokovic 21.

“I like indoors. I like the World Tour Finals,” Federer said. “I back myself to win also matches like these. [But] he was the favorite going in. There was less pressure in this match because regardless if you're going to win or lose, it's still on your racquet to win. I know it's a big win.”

Federer is now 2-0 at the tournament and has qualified for the semifinals; at 1-1, Djokovic can reach the weekend with a win in his next match.

“It's always good beating Novak or any top player moving forward. But still to me, Novak is still the favorite of the tournament. Heavy favorite [to win against Tomas] Berdych [in his next] match, in my opinion. Then he should make his way to the semis somehow…He's far from gone.”