Smelling blood, Smalling tore forward and ignored Phil Jones on the overlap to instead feed Rooney, who prodded through for Nani to net with the most outrageous of cheeky finishes. Nani then made way, along with Anderson, for Ryan Giggs and Park but the relentless attacking continued.
Rooney wedged a golf-like shot of sheer class against an upright before Park exchanged passes with Young to bury a low finish into the corner of the net. Van Persie restored a semblance of pride with emphatic finish after being played onside by Jones but United simply stepped up a gear again.
Jenkinson received a second yellow card for bundling Javier Hernandez over when he was through on goal and there were more illegal tactics used to halt the red tidal wave when Walcott tripped Patrice Evra inside the box. Rooney stepped up to seal his hat-trick with a confident spot-kick and it got even worse for the North Londoners when Young curled in to add his second from a Giggs pass.
Park shot over in stoppage time but enough damage had been inflicted to the Gunners' battered pride as the home fans rejoiced on a day to remember at Old Trafford.