MIAMI (Florida), April 4: American Andy Roddick, the sixth seed, toppled world No 1 Roger Federer in three sets here on Thursday to reach the semi-finals of the Sony Ericcson Open.

Roddick downed the top-seeded Swiss 7-6 (7-4), 4-6, 6-3, leaving Federer still in search of his first title of 2008.

Roddick recorded 17 aces to post the victory in one hour 55 minutes, claiming just his second victory over Federer in 17 tries.

“I’m just glad I have a little hair left,” Roddick quipped about how long it had been since he had beaten Federer.

He earned his only break of Federer’s serve in the eighth game of the third set, allowing him to serve out the match in the next game. Roddick quickly raced to a 40-0 lead, but needed all three of those match points to finally put Federer away.

Federer, ranked number one since February of 2004, has yet to reach a championship match in three tournaments this season.

His defeat here, in the second elite Masters Series event of the season, follows a shocking loss to to then-98th-ranked Mardy Fish in the semi-finals at the Indian Wells Masters Series two weeks ago.

Federer, who has pointed to the debilitating effects of a bout with mononucleosis as one reason for his slow start, hasn’t gone this far into a season without a title since 2000.

Roddick, the 2004 champion, did not play a seeded player en route to his fifth quarter-final in nine career appearances here.

The 25-year-old American has enjoyed a solid season thus far, with an 18-3 mark and titles in San Jose and Dubai.

Roddick will face Russian Nikolay Davydenko in the semi-finals.

Davydenko, the fourth seed, cruised past Serb Janko Tipsarevic 6-2, 6-1.

The 26-year-old Davydenko is off to a career best 17-5 start this season. He became the first Russian man to reach the semi-finals in the 24-year history of the event.

He had little trouble as he fired nine aces and converted five of six breaks points in dispatching the 23-year-old Tipsarevic in 72 minutes.

The other semi-final on Friday pits Spain’s world number two Rafael Nadal against Czech Tomas Berdych.

Meanwhile, defending women’s singles champion Serena Williams beat world No 4 Svetlana Kuznetsova 3-6, 7-5, 6-3 to reach the final on Thursday.

Williams will play world No 3 Jelena Jankovic in the final after the Serbian overpowered Russia’s Vera Zvonareva 6-1, 6-4 in the other semi-final.

Former world No 1 Williams is bidding to equal Steffi Graf’s record of five Miami titles.

The American had been practically flawless in her last-eight victory over world No 1 Justine Henin but made 43 unforced errors against Kuznetsova.

Twice in the first set — after the fifth and seventh games — Williams was on the ground receiving treatment on her back from the trainer.

Three of the first four games of the match were decided by service breaks with Kuznetsova gaining the upper-hand at 3-1.

Serving at 0-40 in the fifth game, Kuznetsova hit a crafty drop shot on the line that turned the game around for her and she went on to take a 4-1 lead.

Williams patiently waited out the second set where she finally scored a service break in the 12th game at 15-40 when Kuznetsova crashed an easy overhead into the net.

However, both players struggled to hold serve in the deciding set.

Kuznetsova surrendered her serve in the eighth game after dumping a backhand into the net, putting Williams in a position to serve out for the match.

The American thumped down an ace to set up match point and then Kuznetsova sailed a backhand long.

Thursday’s results (prefix number denotes seeding):

Men’s singles:

Quarter-finals: 6-Andy Roddick (US) bt 1-Roger Federer (Switzerland) 7-6 (7-4), 4-6, 6-3; 4-Nikolay Davydenko (Russia) bt Janko Tipsarevic (Serbia) 6-2, 6-1.

Women’s singles:

Semi-final: 8-Serena Williams (US) bt 3-Svetlana Kuznetsova (Russia) 3-6, 7-5, 6-3.—Agencies