Federer battles into semis

Roger Federer kept his bid for a first Grand Slam title of the year alive with a straight-sets quarter-final victory over qualifier Gilles Muller at the US Open on Thursday.

Federer was solid if unspectacular in the face of some powerful hitting from the unfancied Luxemburger to close out the match 7-6 (7/5) 6-4 7-6 (7/5).

The four-time defending champion was expected to sweep aside Muller, who had enjoyed a dream run after being ranked 130 in the world before the tournament.

The contrast in the two players' careers was none better illustrated by the fact Federer was gunning for this 18th consecutive appearance in a Grand Slam semi-final, while Muller's best effort was a third-round showing at Wimbledon three years ago.

However, Muller coupled his heavy hitting with the same steely resolve that had helped him edge a five-set thriller against fifth seed Nikolay Davydenko in the previous round to cause the Swiss an uncomfortable afternoon in sweltering conditions on Arthur Ashe Court.

Federer began in confident fashion by breezing through his opening service game before taking a fidgety-looking Muller to deuce on his serve.

The Luxemburger unleashed a couple of hefty serves to extricate himself from the danger and seemingly shed his early nerves.

The match soon settled into a groove with the duo trading service games until, with the score at 6-5, Federer again took Muller's service to deuce.

Muller showed his battling qualities to deny Federer five set points before taking the set into a tie-break.

Federer shot out to a 3-0 lead in the first-set decider, but Muller gritted his teeth in defiance again to draw level at 4-4.

Federer was clearly being tested and spurned another set point before eventually closing it out at the seventh time of asking, firing a passing shot down the line that Muller could only fend wide.

It was more of the same in the second set with Federer unable to find a crack in Muller's power-based game.

The Swiss, however, bided his time and his chance eventually arrived in the ninth game when Muller went for, and missed, a second serve to give Federer three break points.

Muller again showed his resolve to save two of those break points, but Federer's patience paid off as he pounced on a weak second serve before passing a stranded Muller at the net with the flick of his wrist.

The Swiss served out the set without fuss in the next game to suddenly have a stranglehold on the match.

Muller could see his dream run evaporating before his eyes and Federer sensed as much, immediately applying the pressure to take the Luxemburger's first service game to deuce.

Almost unsurprisingly, Muller recovered again to claim the game.

Federer was again forced to sit back and play a waiting game as Muller refused to be overawed by the situation or his opponent.

The duo traded service games, with Muller surviving one break point in the ninth game, before the set went to a tie-breaker.

Muller took an early lead in the tie-breaker, relying on his big serve to claim a 4-1 advantage.

It was Federer's turn to respond and he did so in fine style, clawing back to lead 6-5, but only after a Muller cross-court backhand missed by the narrowest of margins.

From the ensuing match point Muller dumped a forehand into the net which prompted a shriek of delight from a clearly relieved Federer.