Federer gained three match points and won on his first when Kiefer mishit a shot into the roof of the hall.

The top-ranked player, who hails from Basel, is seeking his second straight title here. If he repeats as champion, Federer also will end the year as No. 1 for the fourth straight season.

Federer, who won three of four Grand Slams this year, beat Kiefer for the ninth straight time and is 10-3 against the German. Kiefer made a strong comeback in the second half of the season after missing more than a year with a wrist injury.

Jarkko Nieminen upset second-seeded Fernando Gonzalez 6-3, 7-5.

In his third semifinal of the year, Nieminen will play 2005 runner-up Marcos Baghdatis, who beat eighth-seeded Paul-Henri Mathieu 6-2, 7-6 (5).

Nieminen scored his first win against Gonzalez in five attempts. He wasted two match points while leading 5-4. Nieminen fought off three break points before gaining his third match point and converting it with a backhand down the line.

"I played very good tennis last year, but I could not beat top 10 guys," Nieminen said. "This has been a very up and down year, but I got my confidence back this week."

Gonzalez, who won the Basel tournament in 2005, hurt his chances of qualifying for the season-ending Masters Cup. He is one of 20 players competing for the last three spots at the Masters Cup next month. The event features the top eight players.

"I still have a good chance to go, I am not secure yet but I am very close," Gonzalez said. "It's up to me. If I play well in Paris, I will go."

The Paris Masters is the last tournament before the Masters Cup.