London, Nov 13 (IANS): Top seed Novak Djokovic is one match win away from becoming year-end world No.1 after defeating third seed Stan Wawrinka in straight sets at the ATP World Tour Finals at the O2 Arena here.

Three-time champion at the season finale, Djokovic extended his indoor winning streak to 29 matches with a 6-3, 6-0 victory over Wawrinka Wednesday, reports Xinhua.

"I definitely didn't expect it but hope that I can play this way again and the match result can go this way for me. Obviously Stan wasn't feeling his best today, made a lot of unforced errors and had a low percentage of first serves in. On my side, I just played very solid from all over the court. I think I covered the court very well, got a lot of balls back, mixed up the pace, got him off the comfort zone. That's something that was part of my game plan," Djokovic said..

"After I lost the first two games, obviously I didn't start so great. I thought he played very well the first two games. But, again, I wasn't frustrated. I kept my calm. After that, it was a really amazing performance."

Djokovic fought back from 0-2 down in the opening set by winning 20 of the next 23 points to take a 5-2 lead. Although he committed 14 unforced errors, five fewer than Wawrinka, his serve proved vital in the 41-minute first set. He went on to crush the Swiss in the second set, making him win just seven points.

Djokovic will take on Tomas Berdych in the last group stage match in a bid to qualify for the semi-finals.

Sixth seed Berdych, who lost to Wawrinka in his first match, improved his chances of reaching the last four by beating this year's US Open champion Marin Cilic 6-3, 6-1 in 75 minutes in the afternoon match. Cilic was eliminated with two defeats.

"I felt much better on the court. But still it was not one of my best. That's fair to say. But I think that's the beauty of this event. One day you can be swept out from the court like I did and in two days' time you can come up and you can play a different tennis," Berdych said.