While the blue half of Manchester looked set to dominate the footballing agenda with a stunning 5-1 win at Spurs, United went goal crazy against a depleted Arsenal side to steal the headlines and hammer home a warning to Roberto Mancini's team and the rest of the Barclays Premier League.
In a game that had everything - a missed penalty, a converted spot-kick, a hat-trick for Wayne Rooney, a red card and 10 goals, United simply romped home 8-2.
Danny Welbeck, Ashley Young (2), Nani and sub Ji-sung Park also hit the net with David De Gea superbly saving a penalty when the lead was a slender one. Theo Walcott and Robin van Persie replied for the crestfallen Gunners, who had Carl Jenkinson sent off in the second half.
United made their intentions clear from the start with Welbeck charging down Wojciech Szczesny and looking a real threat. Tom Cleverley and Welbeck shot wide and some of the Reds' passing was mesmeric.
So it was no surprise when the hesitant visiting defence failed to deal with Anderson's clever lofted pass and Welbeck steered a looping header over Szczesny for the opener. Chris Smalling dragged wide after setting up the chance for himself beautifully but, against the run of play, Arsenal were awarded a penalty when Jonny Evans pulled at Walcott's shoulder. De Gea dived to his right to push van Persie's spot-kick around the post and earn the congratulations of his team-mates. And, from United's next attack, Young collected a header out by Armand Traore and bent an inch-perfect curler past Szczesny's despairing fingertips for 2-0.