Arsenal have produced an astonishing first-half display against Manchester United to take a 3-0 lead into the interval.

It was a dream start to the contest for the hosts, who found themselves three goals to the good inside just 20 minutes in North London.

Alexis Sanchez was the first player to breach David de Gea's net, flicking home Mesut Ozil's cross at the near post to put his side on their way.

That came just 74 seconds before Ozil got his own name on the scoresheet to double the Gunners' tally in a similar clinical fashion, as the Germany international coolly slotted Theo Walcott's slide-rule pass beyond a stationary De Gea.

It marked the first time that Arsenal had scored twice against their great rivals in a top-flight game since 2011, and left the rattled visitors with a real mountain to climb in the remainder of the contest.

Only once before in Premier League history had United conceded two goals in a shorter time frame and, while they did show signs of growing into the match a little more, it soon became even worse for Louis van Gaal's men.

Sanchez, in a buoyant mood on the back of his hat-trick against Leicester City last weekend, capped a fine passing move from Arsenal by smashing home number three with less than a quarter of the game played.

The Chilean simply shrugged off the challenge of Matteo Darmian and rifled the ball beyond a rather helpless De Gea to pile the misery on a shell-shocked United.

Having lost just one of their last 13 fixtures against the Gunners in the league, the 13-time champions found themselves three goals down inside the opening 20 minutes of a Premier League game for the first time ever.

Once more Van Gaal's men looked to put some attacking moves together, without truly troubling their opponents, but they could take solace from the fact that they had scored three times in each of their last three outings.

Makeshift full-back Ashley Young and Darmian in particular were being left badly exposed, and that was epitomised 10 minutes before half time when Aaron Ramsey simply ghosted in to side-foot a volley over the bar when he really should have been finding the net.

United, with three league wins on the bounce heading into this one, very nearly pulled one back heading into half time but Petr Cech remained big to deny Anthony Martial on the turn from close range.