United started the game with intent, and immediately put Sunderland on the back foot by winning a succession of corners, although despite their newfound lethality from set-pieces, could not make any of them count, Ashley Young's drive over the bar from 20 yards the closest the home side came to taking the lead.
Instead, it was from open play that United found their breakthrough, Young uncharacteristically stayed on his feet after enduring a strong challenge to put a ball into the area which found Robin van Persie, who had enough time to chest the ball down before volleying it into the top corner, leaving Simon Mignolet with no chance.
Shortly afterwards, United made it 2-0, Michael Carrick getting into space on the edge of the area before playing a slide-rule pass to find Tom Cleverley's run into the box from out wide, the midfielder making a difficult finish from an angle look simple as he curled a finish past Simon Mignolet and inside the far post with ease.
The floodgates appeared to be open at Old Trafford - a rarity for a side that have had so few wins by large margins this season - and Wayne Rooney should have made it 3-0 immediately afterwards as Robin van Persie headed down Ashley Young's cross to the England striker, who tried to be too precise with his shot, aiming for the top corner but shooting wide.
Despite Sunderland rarely managing to venture out of their own half, United did not put them under a huge amount of pressure for the rest of the half and it appeared that, despite their dominance, another narrow win was on the cards for the hosts. James McClean almost undid much of United's good work on the stroke of half-time, getting clear after a bad mistake from Rio Ferdinand, but fired low at David de Gea at the near post when he had options waiting in the box.
After half-time, United resumed their siege of the Sunderland goal, and they continued as they had been previously, with Robin van Persie, Ashley Young, and Wayne Rooney leading the charge. Rooney went close again as he hit the bar from Antonio Valencia's cross, but a few minutes later, he was presented with a chance he simply couldn't miss. Van Persie played a one-two with Young before manifesting on the left-hand side of the Sunderland area, taking a delightful touch to skip in between Titus Bramble and Carlos Cuellar, and cutting back to leave Rooney with an open goal. 3-0 and United were cruising.
The good news didn't end there for United, as they next welcomed back their captain, Nemanja Vidic substituted on to make his long-awaited return from injury. Unfortunately, his arrival also heralded United's failure to keep a clean sheet, as a few minutes later former Red Devils striker Fraizer Campbell came off the bench to head Stephane Sessegnon's cross past David de Gea.
It was of course no more than a consolation for Sunderland, who were fortunate to only lose 3-1 today thanks to some shoddy finishing from a United team that had been all over them for 90 minutes. The play between Wayne Rooney, Ashley Young and Robin van Persie was simply too much for the Black Cats, with the Dutch striker in particular in imperious form. United look like they may be beginning to click - they have all of their most difficult games of the season out of the way already, and have so far past their tests against their title rivals with flying colours. The real worry for their rivals, however, will be that they look like putting the sort of consistency together that truly wins titles. For the first time in a while, United never looked in danger of losing.