Second-ranked Novak Djokovic won 6-4, 7-6 (5), 6-2 to improve his career record against Tomas Berdych to 17-2. The best-of-five series will now be decided in the final match between Radek Stepanek and Serbian cup rookie Dusan Lajovic.

Tomas Berdych and Radek Stepanek defeated Nenad Zimonjic and Ilija Bozoljac 6-2, 6-4, 7-6 (4) on the indoor hard-court at Belgrade Arena. The victory improved the Czech pair's impressive cup doubles record to 14-1.

Novak Djokovic overcame some early nerves to beat Radek Stepanek 7-5, 6-1, 6-4 in the first singles match and Tomas Berdych then swept past rookie Dusan Lajovic 6-3, 6-4, 6-3 on the indoor hard court at Belgrade Arena.

Rafael Nadal, who had already sealed his berth, helped seventh seed Stanislas Wawrinka of Switerland to qualify for the semi-finals. Berdych needed to beat Nadal to ensure his spot in the last four of World Tour Finals.

The 6-3, 6-2 win has put Nadal on the verge of finishing the year as the world number one.

Wawrinka, who has enjoyed the best year of his career, defeated Czech fifth seed Tomas Berdych 6-3, 6-7 (0/7), 6-3.

Playing in the final for the third time in five years, the Czechs also named 44th-ranked Lukas Rosol, Radek Stepanek (46) and Jan Hajek (109) to face 2010 champions Serbia led by world number two Novak Djokovic.

Stanislas Wawrinka seriously dented his hopes of reaching the ATP season final when crashing out of the Swiss Indoors with a 6-4, 6-3 first-round loss to Edouard Roger-Vasselin on Tuesday. Stanislas Wawrinka seriously dented his hopes of reaching the ATP season final when crashing out of the Swiss Indoors with a 6-4, 6-3 first-round loss to Edouard Roger-Vasselin...

Federer opened his Swiss Indoors campaign with a 6-4, 6-2 first round win over Adrian Mannarino at his home town of Basel on Monday.

Rafael Nadal, who improved to 27-0 on hard courts this season, will return to the top ranking for the first time since July 2011. Novak Djokovic has been No. 1 for 101 weeks.