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Manchester United beat Arsenal 2-0 at Old Trafford in the FA Cup sixth round, as the Gunners crashed out of their third cup in 13 days.

Goals in either half from Fabio and Wayne Rooney booked an injury-ravaged United side's place in a Wembley semi-final, while Arsenal's misery was compounded following their Carling Cup final defeat to Birmingham and Champions League exit at the hands of Barcelona.

A personnel crisis forced Alex Ferguson to name seven defenders in his starting XI but, for United, every cloud has a silver lining - or in this case a Silva one.

Brazilian twin full-backs Rafael and Fabio da Silva were pushed into the wide midfield positions. Freed of their defensive shackles, they ran at Arsenal with a pace and directness reminiscent of (though less refined than) Gareth Bale, who also made the transition from full-back to winger.

It represented a pleasant surprise for United fans whose hearts must have sunk on viewing the team sheet. Michael Carrick and Darren Fletcher were the latest additions to a lengthy injury list, rated by Ferguson as having "no chance" of playing against Marseille in the Champions League on Tuesday. Ryan Giggs and Paul Scholes began on the bench, resting their ageing limbs.

Having spent Tuesday night chasing the shadows of Andres Iniesta and Xavi, the prospect of facing a central midfield comprising Darron Gibson and John O'Shea must have come as a blessed relief to Arsenal.

As for the Gunners, there was no Cesc Fabregas, who struggled through 78 minutes at the Camp Nou despite being clearly unfit. Robin van Persie did start, after the red card for kicking the ball away that so enraged Arsene Wenger and accelerated Arsenal's European exit.

Arsenal made the better start, using the ball more effectively, freed from the suffocating pressure exerted by Barcelona.

Even with Van Persie, captain for the day, chances were few and far between. The Dutchman forced his countryman Edwin van der Sar into a save with a low cross-shot and might have done better with a header from a corner, while Samir Nasri's low shot tested Van der Sar late in the first half.

United's moments of attacking quality were few, but they produced a move of decisive brilliance on 28 minutes.

Rafael found Rooney from the right, whose curled diagonal ball had the perfect weight for Javier Hernandez. The Mexican's powerful header was parried by Almunia and Fabio arrived to tuck the rebound into the roof of the net.

The Da Silva twins were withdrawn as Ferguson sought some more streetwise heads to protect the lead, and it was his oldest player, goalkeeper Van der Sar, who made a clutch of vital interventions.

The 40-year-old has 21 professional seasons under his belt to Giggs's 20, but showed his powers are undimmed.

The Dutchman made a string of top-class saves - the best among them a brilliant reflex stop from Laurent Koscielny, and a diving parry to repel a Marouane Chamakh header.

No wonder United want him to postpone his retirement, scheduled for the end of this season.

Antonio Valencia made a promising cameo having spend six months out with a broken ankle, while Aaron Ramsey made his first Arsenal appearance since suffering a broken leg a year ago.

Paul Scholes, brought on for his experience, should have been sent off in stoppage time when, seconds after being booked, he threw himself into a lunging challenge then pushed Samir Nasri. Chris Foy showed the 36-year-old excessive leniency.

A dreadful fortnight for Arsenal ended with a potentially serious injury to Johan Djourou, who dislocated his shoulder in a collision with a team-mate; play was stopped for five minutes while medics administered treatment. Djourou was stretchered off, and is expected to miss the rest of the season.

Arsenal's four potential trophies are now down to one, and Arsene Wenger faces one of the biggest tests of his career rousing his beleaguered troops ahead of the Premier League run-in.
Alex Chick / Eurosport