Halle: Top seed Roger Federer will challenge for a ninth Halle Open title against Alexander Zverev after reaching the Wimbledon warm-up event final with a 6-4, 7-6 (5) win over rising Russian talent Karen Khachanov on Saturday.

The 18-time Grand-Slam champion, who captured the Australian Open, Indian Wells and Miami titles this year, skipped the entire clay court season to improve his chances of winning a record eighth title at the All England Club.

He will now face 20-year-old Zverev in a rematch of last year's semi-final, which the German won. Zverev booked his second successive final spot when he beat Frenchman Richard Gasquet 4-6, 6-4, 6-3.

Despite a shock exit from Stuttgart on his comeback last week, Federer has improved in Halle and has not lost a set.

"I thought it was extremely close, especially that second set," Federer, who has never won a tournament nine times, told reporters.

"I'm still just very happy how I was able to close it out in the tie-breaker," said the 35-year-old.