Bendtner sends Gunners through

Fran Merida, who is out of contract in the summer, opened the scoring at the Emirates Stadium with a spectacular drive before Emiliano Insua levelled with a dipping lob before the break for Liverpool.

Denmark striker Bendtner finished off a sweeping move constructed by Wenger's youngsters just after the interval for the winner in the fourth-round clash.

The hosts started well, and Merida - who almost went out on loan to Levante, only for Wenger to pull the plug on the deal at the last minute - fired a low effort just off target.

Liverpool created a decent opening when a clever backheel from David Ngog, on target at Anfield to help sink United, released Philipp Degen on the edge of the penalty area, but the Swiss defender dragged his shot across the face of goal.

Merida opened the scoring with a fine strike on 19 minutes. Craig Eastmond, 18, stole possession on the right, and the ball broke for Merida, who promptly smashed a first-time, left-foot shot in off the post past Diego Cavalieri.

Arsenal, though, had their lead only until the 26th minute when Insua netted a fine equaliser. A long ball up field was knocked down by Ryan Babel, and it dropped perfectly for Insua, who drilled a looping shot up over Lukasz Fabianski from 25 yards for the Argentinian defender's first goal in English football.

There was a let-off for Liverpool when Cavalieri dropped the ball in a crowded six-yard box, but enough black shirts were around to clear.

Arsenal kept up their momentum following the restart, and went ahead again five minutes into the second period. A sweeping move saw Merida feed the ball through to Bendtner on the penalty spot and the Denmark international held off Skrtel before smashing his shot into the roof of the net.

Liverpool almost snatched an equaliser when Kuyt swept the ball across the six-yard box, but Babel, sliding in, just could not make contact. Eduardo drilled his shot wide of the far post, but Arsenal had done enough to secure a place in the last eight.