Five-time champion Roger Federer will face “mystified” German Tommy Haas in the final of the ATP grasscourt tournament after the two tour veterans clinched straight-sets semi-finals wins on Saturday.

Roger Federer celebrates after winning a point in Halle. Pic/AFP

Federer reached the Halle final for the seventh time after a 6-1, 6-4 victory against unseeded Russian Mikhail Youzhny. Wildcard Haas, a former world number two, defeated compatriot Philipp Kohlschreiber, the quarter-final conqueror of Rafael Nadal, 7-6 (7/5), 7-5, and admitted later it was a mystery how he managed to reach the final.

Second-seeded Federer showed few signs of fatigue despite scraping past Canada’s Milos Raonic in a third-set tie-break in the last eight on Friday, and needed barely an hour to see off the world number 31 Youzhny.

Federer fired down eight aces, and remains on course to win the Wimbledon warm-up event for the sixth time. He later claimed that saving three break points in the fifth game of the opening set was vital to his ultimately comfortable win. “The key for me was coming back from 0-40 then holding that and going 4-1,” said Federer¬†