London, Nov 27 (DPA) Rafael Nadal and Novak Djokovic both won their final Group A matches in straight sets Friday to finalise the semi-final line-up at the ATP World Tour Finals.

World number one Nadal beat Tomas Berdych in a replay of the summer's Wimbledon title match 7-6 (7-3), 6-1.

Serb Djokovic managed to conserve energy for his Davis Cup finals date - in a week at home in Belgrade against France - with his 6-2, 6-3 win over US player Andy Roddick, who ends his season 0-3 in the group stage after his eighth consecutive year-end appearance.

Roddick had won his last four meetings with Djokovic dating to the Australian Open in January 2009.

Nadal finishes first in the group and will play Saturday against Scot Andy Murray.

Djokovic faces Roger Federer, who has not dropped a set this week in the season wrap-up. Djokovic predicted that the match could "come down to maybe a couple of points."

"It's a big challenge for both of us," he said.

Federer will be bidding for a fifth career year-end title, while Nadal and Murray are seeking a first. Nadal won the honours in 2008.

Nadal's indoor win marked his eighth straight against Berdych, who last beat the Spaniard in 2006 at Madrid in an ill-tempered match where the winner angered the home crowd. Nadal's latest success in the series, in which he now stands 9-3, came in the Wimbledon final in July, where the Spaniard beat Berdych without dropping serve.

"I'm very happy. It's a very good end of the season, (regardless of) the result of tomorrow," Nadal said. "To finish the season winning all the matches in the group, three victories against top eight players in probably the most difficult surface for me, is unbelievable now. It's great to be in the semifinals."

Nadal's first set with Berdych lasted in excess of an hour, with the Spaniard getting annoyed while trailing 5-6 and 15-30, when he had words with the chair umpire about a Berdych shot called long but reversed on a Hawk-eye electronic challenge.

Despite his anger after the point was awarded to the Czech, instead of a replay of the point being called, the Spanish world number one regained his concentration and sent the set into a tiebreaker, which he won to put one foot into the Saturday
semifinals.

After his close-call while standing two points from defeat in the first set, Nadal then put his foot down against Berdych, against whom he has not lost a set since 2006.

"I was playing really well before that point," Nadal said.

"This point doesn't change a lot. Finally I was lucky. I won that game. Finally I won the match. I was still playing the same level before that point and after that point. But maybe Tomas went down a little bit in the second, and I feel every time better and better. The point didn't make any effect on the match."

The win came after just under two hours, with Nadal breaking twice and profiting from six double-faults from the Czech. Nadal lost all three of his group matches in 2009, coming into the year-end event injured.