HALLE, Germany -- Roger Federer blew past Mischa Zverev 6-0, 6-0 to reach the Gerry Weber Open semifinals on Friday, teaching a painful lesson to a player trying to serve and volley on grass, the surface best suited for such a game.
Federer will play defending champion Tommy Haas, who beat him in last year's final. The German came from behind to beat Gael Monfils 6-7 (4), 6-3, 6-3.
"Hopefully, I'll do a little better than Mischa," Haas said.
Second-seeded Richard Gasquet also made the last four, beating eighth-seeded Florian Mayer 6-3, 7-6 (4) to stay on course for a third title this year.
Gasquet will play Mikhail Youzhny, who upset 2011 champion Philipp Kohlschreiber 6-3, 6-2. Youzhny's only victory in eight previous matches against the sixth-seeded Kohlschreiber was when the German had to retire after one set in 2007.
The top-seeded Federer needed only 39 minutes to record the second "double bagel" of his career. The first was over Gaston Gaudio at the Masters Cup in Shanghai in 2005.
"It's not something which is easy to do. You never go into a match aiming for that score," Federer said. "I was very surprised that it happened today, especially on grass.
"I think it is disappointing for a serve-and-volley player to go down like this. It shows also how easy it is to hit passing shots or returns today."
Zverev, a German wild card ranked No. 156, stuck to his game plan and paid the price for it.
"I hope he doesn't take it too badly," Federer said. "I just had a pretty easy time picking up his serve and I must have made a ton of returns."
While saying he would rather win 6-1, 6-2, Federer said gifting Zverev a game never crossed his mind. He said the only time he lost 6-0, 6-0 was his first match, at age 8.
Zverev took his loss in stride.
"I'd rather lose 6-0, 6-0 to Roger in a quarterfinal" than to a qualifier in the second round, Zverev said. "At least there is something to talk about later."
Federer is looking for his first title of the year and his sixth on the grass court at Halle, his favourite tune-up for Wimbledon. Federer has seven Wimbledon titles and will be the defending champion there. Four of his Wimbledon titles have come after triumphs in Halle. But his last title in Halle was in 2008.
"It's been a long time since I won here, so that title this year has the highest priority for me," said Federer, who owns a record 17 Grand Slam championships.
Haas is the oldest man in the top 100, currently ranked No. 11 at age 35 and enjoying a second spring. He already has a title this year at home, in Munich.
Monfils thrilled the crowd with his acrobatic, nonconventional shot-making. Once, he let a high ball bounce between his legs, twisted around and hit a smash on the turn. The smash was good but he lost the point on an error. He also dived and jumped high to hit overhead shots that pleased the crowd. The third-seeded Haas was perhaps less spectacular but more effective and simply made fewer errors.
"It was close, he was lucky to hit a few lines at the end," Monfils said. "I play such points to win them, not just to have fun."
Haas teamed with good friend Federer to play rare doubles in Halle but they lost in the first round.
"You always look forward to such matches. Roger is one of the greatest players of all time. It's something real special," Haas said.
Mayer produced a pair of stunning diving winners but Gasquet was the steadier player and fired an ace to finish the match.
"It was a tough match for me because he is a good player and I lost to him last year in Wimbledon," Gasquet said. "I played very solid."