Briton Andy Murray celebrated his entry into the world's top 100 by beating U.S. Open semi-finalist Robby Ginepri 4-6, 6-4, 6-3 to reach the last four of the Thailand Open on Friday.

The 18-year-old Scot, who started the year ranked 411, defeated the American third seed to clinch the second best result of his career after his second round Wimbledon [Images] defeat of 15th-ranked Radek Stepanek.

Further good news for Murray was that second seed Lleyton Hewitt [Images], his likely semi-final opponent, withdrew with a leg injury against Paradorn Srichaphan [Images], handing the seventh-seeded Thai a walkover.

"Winning against two top 50 players in a row is a pretty big deal for me, and to get to my first semi-final is also great," said Murray.

Top seed Roger Federer [Images] eased past Gilles Muller of Luxembourg 6-4, 6-3 and will meet Jarkko Nieminen in the semi-finals. The sixth seeded Finn ended the run of Taiwan's Yeu-Tzuoo Wang, winning 6-4, 6-7, 6-4.

Murray broke serve in the opening game of the match when Ginepri double-faulted, combining fine returns and strong serving to build a 3-1 lead.

The set was turned on its head when Murray suffered an inexplicable lapse, losing 12 out of 13 points as Ginepri broke back twice to take the first set.

Serve dominated the second set until the ninth game when Murray broke, courtesy of a backhand pass down the line.

NEW LEVELS

Gaining in confidence, Murray raised his game to new levels in the decider, unleashing powerful forehands to keep Ginepri under pressure.

The American cracked when he double-faulted to give the Scot a 3-2 lead. His frustration boiled over and he received a warning for racket abuse. Murray broke again to claim victory and a place in his first ATP semi-final.

"Obviously Paradorn is playing in front of his home crowd and he's a big star over here," said Murray. "It's going to be a big match for me and I'm looking forward to it.

"I would like to get through to the final and play my first ATP final against the best player in the world."

Federer needed patience but had little difficulty in disposing of Muller, who recently sprung the biggest surprise of the U.S. Open by bouncing Andy Roddick [Images] from the first round.

The Swiss world number one broke on his fifth break point in the opening game and held further break points at 3-1 and 4-2, although Muller often played his way out of trouble with a blistering serve.

Federer had to wait for a further 54 minutes to earn his second break of the match. Two consecutive double-faults at 5-3 led to Federer claiming a third break and the match.

"It was a dangerous match," said Federer. "Thank God I got off to a good start and that calmed things down a little bit.

"I really tried after that, every service game I played, to stay very focussed and not give him too much of a chance. I don't remember him having any break points so I was never under pressure too much."

"Today was just solid and consistent, what was needed. No real flashy play, and that's probably what I've got to do again tomorrow."

Hewitt struggled in both his opening matches in Bangkok and he saved four match-points against Justin Gimelstob before advancing to the quarter-finals.

"In my practice today I overstretched the inside left of my groin which had been stiff from training and especially after the match over Gimelstob last night," said Hewitt.

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