Man Utd 4 - 0 Wigan
Manchester United's attacking trio of Carlos Tevez, Cristiano Ronaldo and Wayne Rooney put their side top of the table for the first time this season.
United suffered two more injuries in the first half when Nemanja Vidic and John O'Shea had to go off, two substitutions that disrupted the champions' impressive early rhythm.
But the disruption proved only temporary and two goals in the space of four minutes early in the second half ended Wigan's resistance at Old Trafford.
Wigan goalkeeper Chris Kirkland had to react quickly to palm away Salomon Olembe's attempted clearance following a Tevez cross as United began their seige of the visitors' goal. Ronaldo gathered up the loose ball and looked to be clearly fouled by Michael Brown, but referee Mike Riley waved play on.
Towards the end of the first half United recaptured their early momentum, Ronaldo forcing a save from Kirkland, while Tevez wrong-footed Mario Melchiot before curling the ball over the bar.
United began the second half in ominous mood with Ryan Giggs striking the crossbar with a well-executed half-volley.
Tevez's goal provided ample demonstration why Ferguson was so keen to bring the Argentine to Old Trafford. The former West Ham forward had the speed and strength to hold off Kevin Kilbane, before drilling a shot into the corner of the net.
Four minutes later Ronaldo headed in from close range after a United corner and the Portuguese forward capped a fine performance with a cool finish after he had been set up by Rooney.
The England international completed the scoring with a header after Danny Simpson had crossed from the right.
Man Utd: Kuszczak, Pique, Ferdinand, Vidic (Anderson 21), Evra, Ronaldo, O'Shea (Simpson 30), Scholes, Giggs, Rooney, Tevez (Nani 81).