World No. 1 Rafael Nadal defeated the sixth seed Tomas Berdych from Czech Republic in straight sets on Friday, reaching the semifinals at the ATP World Tour Finals with three victories.

Nadal, 24, locked horns with Berdych again after beating the Czech in the final of the Wimbledon Championships in July. The Spaniard needed a 7-3 win in the tiebreak to take the first set but powerfully broke twice later to win the second set 6-1.

"It's a very good end of the season no matter what will be the result of tomorrow," said Nadal who is going to fight for a final place with British top player Andy Murray.

"For me, finishing 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."

Last year, Nadal lost three group matches in a row at the season finale, even without winning a set. But the genius came back strongly this year with three Grand Slam titles and was eager to make a hit in the year-ending tournament which he had never won before.