(CNN) -- World No. 1 Rafael Nadal prevented Novak Djokovic from reaching the semifinals of the ATP World Tour Finals and kept his own hopes alive by beating the Serbian in London on Friday night.
The Spaniard notched his second Group A win this week, triumphing 7-5 6-2 in the season-ending men's tournament.
He will face Tomas Berdych on Friday in a rematch of this year's Wimbledon final, with the Czech having earlier earned his first victory with a result that left American eighth seed Andy Roddick needing to win his final match in straight sets.
Nadal is seeking to reach the final for the first time, having failed to win a match at the same venue last year.
He defeated Djokovic in the U.S. Open final in September to complete his collection of Grand Slam titles, and needed to overcome a strong first-set challenge this time from the world No. 3.
Djokovic, who beat Berdych in his opening match, appeared to be the stronger player in the early games but then had his serve broken by Nadal before immediately replying in kind.
Nadal broke again in the 11th game and held serve to claim the first set as Djokovic appeared troubled by problems with his contact lenses, then raced to a 4-0 lead in the second set before winning in one hour and 52 minutes.
"It was a very good match for me. I was very sorry for Novak for what happened with his eye, I hope he is okay. It was my best match in this tournament," Nadal told reporters.
The 23-year-old Djokovic said he was disappointed he was not given more time to solve his eye problem.
"I'm just really annoyed by the fact that something like this can affect the match. It did because my right eye got irritated and from the five-all I could not see a ball, especially the return. It was just terrible," he told AFP.
"I don't want to find any excuses for my loss, but the fact of the matter is that I just could not play. I needed some time to make it right, but I didn't have time. Everybody was hurrying me up, saying come to the court, play your match."
Berdych, who lost to Nadal in the final of this year's third Grand Slam in July, won 7-5 6-3 against Roddick as he saved two set-points at 4-5 on his serve in the opener.
The 25-year-old then stunned his opponent with a winning forehand return off a 110-mile-per-hour second serve and was untroubled as he closed out the set.
The sixth seed hit 28 winners and made 27 unforced errors, while winning 12 of 16 net approaches and serving six aces.
"The last couple of weeks, I was in this position many times but not often was I able to get back, to do a couple of good serves, get to deuce, then win the game," Berdych said.
"That's the thing that's going to give you a lot of confidence. Then the next game I managed a quick break and that was the key to the match."
Roddick, who lost his opening match to Nadal after qualifying for the event for the eighth consecutive year, will play Djokovic in the closing Group A match on Friday evening.
On Thursday, second seed Roger Federer takes on No. 4 Robin Soderling in their third Group B match, then Britain's Andy Murray plays Spain's David Ferrer.
Federer has won both matches so far, while seventh seed Ferrer has lost his two.
No. 5 Murray and Sweden's Soderling both have a 1-1 record.