HALLE (SAALE), Germany (AFP) - Seven-time champion Roger Federer on Friday reached the Halle semi-finals where he will face Croatian giant Ivo Karlovic who fired a record-breaking 45 aces in his last-eight clash.

World No. 2 and top seed Federer defeated Germany's Florian Mayer 6-0, 7-6 (7/1) as he continues his build-up to an assault on an eighth Wimbledon title.

Federer required just 19 minutes to take the first set against Mayer before going on to conclude the tie in a little over an hour.

Karlovic battered his way into the semi-finals by smashing 45 aces past a bewildered Tomas Berdych en route to a 7-5, 6-7 (8/10), 6-3 victory.

The 36-year-old Karlovic, who stands 2.11m (6ft 11in) tall, won the match with the last of his aces and now has 94 on the Halle grass courts from three rounds of tennis.

"I'm extremely happy about the record," Karlovic said of his battery of aces, a new record in a best-of-three set match.

"Hitting aces helps a lot, you can avoid the volleys. I was surprised when I was told on court after the match how many aces I hit. I didn't know it was that many. Hopefully, I can continue like that in the semi-final."

His record came just two days after Germany's Sabine Lisicki blasted 27 aces in a match in Birmingham - a new record for the women's tour.

Japan's world No. 5 Kei Nishikori also landed in the semi-finals after beating Poland's Jerzy Janowicz 6-4, 5-7, 6-3.

Second seed Nishikori will take on the winner of the match between Frenchman Gael Monfils and Italy's Andreas Seppi.

Nishikori, 25, took two and a half hours to make the final four for the second year running.

Last year, after beating Monfils in the quarters, Nishikori was defeated by Federer, who went on to win the tournament for a seventh time.