INQUIRER Sports

NEW YORK -- Four-time defending champion Roger Federer advanced to his 18th consecutive Grand Slam semi-final on Thursday, stretching his US Open win streak to 32 matches and moving closer to a 13th Slam crown.

The Swiss second seed, who last missed a Slam semi-final at the 2004 French Open, defeated 130th-ranked qualifier Gilles Muller 7-6 (7/5), 6-4, 7-6 (7/5) to end a dream run by the Luxembourg left-hander.

"I'm happy to keep the semi-final streak alive. That's a huge streak for a long time," Federer said. "I'm really happy with my mindset going into the semi-finals. I'm happy to take it to the final four one more time."

Federer next faces the winner of a later quarter-final between Serbian third seed Novak Djokovic and US eighth seed Andy Roddick. Federer is 15-2 against Roddick and 6-2 against Djokovic, including a 2007 US Open final triumph.

The other men's semi-final will send British sixth seed Andy Murray against Spanish world number one Rafael Nadal, who seeks his third Slam crown in a row after beating Federer in the French Open and Wimbledon finals.

"Hopefully I can take it one more step than I did at the French Open and Wimbledon," Federer said.

The Swiss ruled the rankings for 237 weeks until last month, when Nadal ended his reign before capturing singles gold at the Beijing Olympics.

"You could see why he was number one," Muller said. "Every time the score was tight he came up with the better shot."

Federer, 27, has not lost at the US Open since David Nalbandian beat him in the fourth round in 2003. But his aura of invincibility has been punctured this year after seasons of utter domination.

"It's not too much about Roger's invincibility. He's human," Muller said. "Everyone knew he had a tough year. He struggled a little bit. It's more the belief I had in myself, the confidence that I could beat him.

"I could have won the two tie-breakers for sure. I just wasn't so lucky."

Federer won the only break of the match in the ninth game of the second set on a forehand winner. Muller denied Federer on three break points in the third set on the way to a tie-break, then grabbed a 4-1 edge before Federer rallied.

"It was really difficult - the sun, the wind and he was serving great," Federer said. "That's why straight sets is the best result."

Federer blasted a backhand winner to grab his first match point at 6-5 and Muller netted a backhand to end matters after two hours and 26 minutes.

"I'm happy I was able to come back and pull it out because it looked like it was going to go four," Federer said. "When you are down you try to fight and that's what I tried to do out there."

In the first tie-breaker, Federer rescued several shots in a long rally and then fired a backhand winner to grab a 6-4 lead.

Muller, who has spent more than four hours longer on the court at the Open than Federer, answered with a service winner but sent a backhand crosscourt volley wide on the next point to give Federer the set.

"He showed why he was so dangerous," Federer said. "It was hard just to get solid contact on his serve. It was the same for him for a while. There was not much rhythm out there."

Muller, who twice rallied to win here after losing the first two sets, upset Russian fifth seed Nikolay Davydenko in the fourth round to become the second qualifier in the US Open final eight after France's Nicolas Escude in 1999.

"A lot of people think I should be happy but I'm disappointed because I feel like I had my chances and I didn't take advantage of them," Muller said.