Halle Open: Roger Federer moves into 13th straight semi-final, Alexander Zverev beats Philipp Kohlschreiber

Berlin: Roger Federer eased closer to a ninth title at the Halle grass court tournament on Friday when he demolished defending champion Florian Mayer of Germany 6-3, 6-4 in the quarter-finals.

The World No 5, building up to an assault on an eighth Wimbledon title in July, will next face Karen Khachanov, who defeated fellow Russian Andrey Rublev 7-6 (10/8), 4-6, 6-3 in his last-eight clash.

Federer, 35, has yet to drop a set after three matches in Halle this week while his win on Friday took his head-to-head record against Mayer to 8-0, with five of those wins coming on grass.

“It was important to be aggressive off the baseline and make him feel my variation and the power I can bring to the court,” said top seed Federer who has now reached the semi-finals in Halle on 13 consecutive occasions.

“And then having good footwork, to see the short ball, the floater, where I can come in and knock it off with a volley. I think I did it very well. I had lots of chances to even go up a double break in the second set.”

Federer, who hit 11 aces and 32 winners, said facing Khachanov on Saturday will present a new challenge for him.

“It will be interesting. He’s big and strong and seems super excited to be on tour and he’s working hard,” said the Swiss.

“I don’t know him that well yet so it’s a match where I’ll most likely focus on my own game. Make sure I serve well, because he can go through spells where he can serve big. It could be somewhat similar to how I played today.”

Saturday’s other semi-final will see German fourth seed Alexander Zverev face Frenchman Richard Gasquet.

Zverev defeated Spanish seventh seed Roberto Bautista Agut 6-7 (6/8), 7-6 (7/1), 6-1 while Gasquet saw off Robin Haase of the Netherlands 6-1, 3-6, 6-1.