Rafael Nadal of Spain rallied to beat Russian Nikolay Davydenko 5-7, 6-4, 6-4 Friday and set up a Masters Cup semifinal against top-ranked Roger Federer while Daniel Nestor of Toronto and Mark Knowles of the Bahamas advanced to the doubles final four.

Nestor and Knowles defeated Poland pair Mariusz Fyrstenberg and Marcin Matkowski 6-3, 6-3 to finish second in the Gold Group and will face Red Group winner Paul Hanley and Kevin Ullyett in the semis.

American James Blake topped the Gold Group despite losing 6-2, 3-6, 7-5 to Spain's Tommy Robredo later Friday in the last round robin match.

Blake opened the season-ending championship with wins over No. 2 Nadal and No. 3 Davydenko and had secured a semifinal against defending champion David Nalbandian before the Robredo match.

He saved match points in the eighth and 10th games of the second set but pulled a forehand wide after Robredo earned his third match point with a clean backhand winner.

Nadal had more to play for against Davydenko, and took a while to get rolling.

Friday's win was ``my best performance in a long time,'' Nadal said. ``I won a very, very difficult match against the No. 3 in the world, and in his best performance. It was one of my best wins of the year.''

He let Davydenko dictate from the baseline in the first set, who used fast, flat ground strokes to work him side to side. But Nadal varied his game in the second, using more slice and top spin to force Davydenko to run.

Two games after winning the second set, Nadal needed a medical time out to massage and tape his left knee. Nadal said it was a bone spur, and it did not appear to hinder him. He closed out the match when Davydenko's forehand went out.

Nadal is 6-2 overall against Federer, and the only player in the elite eight-man draw with a winning record against the Swiss star.

Despite soreness in his left knee, Nadal said he's in good shape and confident he'll be fit for Saturday's semifinal against Federer.

Federer defeated Andy Roddick, Nalbandian and Ivan Ljubicic to finish atop the Red Group in the round-robin stage. He is on a 27-match winning streak and will be more confident on hard courts against Nadal and with an extra day of rest.

Federer ended a five-match losing streak against the Spaniard when he beat Nadal in the Wimbledon final.

Nadal has won five titles and made six finals in 15 previous tournaments this year, but has not reached a semifinal since Wimbledon. He has been more aggressive with his serve and forehand and believes it's starting to pay off.

``To be in the semifinals is very important for me,'' Nadal said.

It was the first meeting between Nadal and Davydenko, who has won five titles in 31 events.

Davydenko ran out of energy in the deciding set against Nadal, as he did after leading Blake by a set and break before losing.

``I was fit, was feeling great,'' Davydenko said. ``Then came some long rallies. That's when I was feeling a little bit tired and did some mistakes. That's when I started losing.''

In the other doubles match Friday, second-seeded Jonas Bjorkman and Max Mirnyi finished the Gold Group round-robin stage unbeaten with a 6-3, 7-6 (7) win over Fabrice Santoro and Nenad Zimonjic.

In the semifinals, Bjorkman-Mirnyi will face Martin Damm and Leander Paes.

© The Canadian Press, 2007