HALLE, Germany (AFP) - Four-time winner Roger Federer outclassed Germany's Mischa Zverev 6-0, 6-0 on Friday to book his place in the semi-finals of the Halle Open.

The world No. 3 will play the winner of the quarter-final between Germany's Tommy Haas, who beat him in last year's final, and France's Gael Monfils.

The 31-year-old Federer wrapped up the first set in just 20 minutes, then concluded the second - and the match - 39 minutes later against the world No. 156.

The "double bagel" whitewash is the second of Federer's career. His first was inflicted on Argentina's Gaston Gaudio in the semi-final of the Shanghai indoor tournament on November 14, 2005.

In Halle, the Swiss was even more efficient than in his opening 6-3, 6-3 victory over another German qualifier, world No. 166 Cedrik-Marcel Stebe, in 67 minutes.

Federer, who has won a record 17 Grand Slams, is still out to win his first trophy of the season and now has 41 wins and just five defeats on the grass at Halle.