Roger Federer beats Ivo Karlovic to reach Gerry Weber Open final

Roger Federer will play either Andreas Seppi or Kei Nishikori in the final

World number two Roger Federer eased into the Gerry Weber Open final with a straight-set victory over Ivo Karlovic.

The Swiss top seed won 7-6 (7-3) 7-6 (7-4) to move closer to a record eighth title in Halle, Germany.

Karlovic, 36, hit 45 aces - the most in a three-set ATP Tour match - against Tomas Berdych in the last eight.

Federer, 33, was unable to secure a single break point against the Croat but won both tie-breaks to set up his 10th appearance in the event's final.

A brilliant backhand return followed by a Karlovic double fault secured Federer the first set and he went on to seal victory after one hour and 28 minutes with a backhand volley in the second tie-break.

"Sometimes you can't do anything," Federer said of Karlovic's serve. "You have to hope for a bit of luck or that you don't make a mistake at an important moment.

"The whole match can change in a moment. Thankfully it went well, though I had a bit of luck in the tie-break."

Federer will meet Italy's Andreas Seppi in Sunday's final after second seed Kei Nishikori retired early with a calf injury after the fifth game of the other semi-final.

The 25-year-old world number five, who was trailing 4-1 when he retired, said: "I felt it yesterday during the quarter-final and I fought through it.

"But there was a little pain this morning and I tried in the match, but couldn't really move.

"I don't want to take a big risk for Wimbledon."