The defending champion will play Jarkko Nieminen, who advanced to his first final of the year by beating Marcos Baghdatis 7-6 (4), 6-2.

A win for Federer can clinch his season at No. 1 for the fourth consecutive year.

Federer saved one set point in the 10th game with a passing shot out of reach for the 6-foot-10 Karlovic, the tallest man on the tour. Federer wasted two set points in the tiebreaker but then won it with an overhead smash.

Karlovic produced an ace, one of his 16, and a volley to save two match points in the 10th game of the second set. Federer couldn't convert one more in the tiebreaker but a forehand into the net by Karlovic put Federer into his 11th final of the year.

The Swiss has won six titles, including three Grand Slams. Federer is 11-0 in his semifinal matches this year. Nieminen is 0-7 against Federer.

"It will be a great experience to play him on his home court," Nieminen said. "Sometimes it feels like he is not a human, but he is and every match starts from 0-0."

Nieminen saved match points in his first two matches at the tournament. The 29th-ranked Nieminen has lost five of six career finals. He won his first ATP title last year.

"I lost a lot of tight matches this year but saving those match points here gave me a lot of confidence," Nieminen said.

Baghdatis, runner-up in Basel two years ago, lost the first set on a double-fault in the tiebreaker and dropped his serve in the third game of the second. Nieminen then cruised to improve his career record to 2-2 against Baghdatis.

"I was tired from last night's doubles, I went to bed very late and didn't sleep well," Baghdatis said.

He teamed with Stanislas Wawrinka, winning to reach the semifinals in a match that ended past midnight.