Goals from Wes Brown and Wayne Rooney sealed an impressive away victory as United totally dominated Blackburn Rovers on their own patch.
The Reds called the tune from start to finish at Ewood Park and, although Blackburn protested long and loud about the award of Brown's first-half goal, there was no question that Sir Alex Ferguson's side were deserved winners.
Rovers goalkeeper Jason Brown claimed that he was fouled as Brown headed in a Wayne Rooney corner, but the rookie stopper was otherwise kept busy restricting United to a respectable scoreline.
After a slow, stop-start beginning to the season, there have been signs in recent weeks that the Reds have been creeping towards top form, and this latest display is the clearest indication yet that the champions have hit their stride.
Sir Alex opted for an attacking line-up as he sought to extend a three-game winning streak, with Dimitar Berbatov and Cristiano Ronaldo selected upfront alongside Rooney, who overcame an ankle injury sustained in Tuesday's win over Aalborg.
For all the Reds' attacking talent, however, it was Nemanja Vidic who almost opened the scoring, but the Serbian centre-back couldn't quite contort to convert Rooney's deflected left-wing corner.
Ewood Park has hardly been a happy hunting ground for United in recent seasons, and Matt Derbyshire served notice of Rovers' threat after 14 minutes when his low shot forced a fine save from Edwin van der Sar.
That was the hosts' most promising piece of play, though, as United called the early tune. Darren Fletcher slid a clear opening wide and Giggs forced a marvellous save from Brown, but the Reds took the lead from the resulting corner.
As players jostled for position to meet Rooney's inswinging cross, the Rovers goalkeeper found his route to the ball blocked by Vidic - who had eyes only for the ball - and Brown was on hand to sneak a header inside the near post.
Jason Brown was called upon to save well at Rooney's feet shortly before half-time as - bar a routine save by van der Sar from Roque Santa Cruz - the Reds' dominance of possession and play continued long into the second half.
Just after the hour mark came the killer second goal. Brown burst out of defence and found Ronaldo, who outmuscled Martin Olsen before pulling back for Rooney to stylishly finish into the top corner.
A third goal in as many appearances for Rooney, who has responded perfectly to being benched against Bolton Wanderers last weekend, and he almost hit number four shortly afterwards, but his neat lob clipped the roof of Brown's net.
Berbatov, Ronaldo and substitute Carlos Tevez, who struck the post with a superb 20-yard effort, all came close to adding gloss to the scoreline, but the Reds couldn't find a way past Brown again.
Blackburn could count themselves lucky to suffer only a two-goal defeat after being bewitched by a swaggering masterclass from United. Less relieved will be those who most covet the Reds' Premier League crown, who saw the clearest sign yet that the champions are approaching top form.
BLACKBURN ROVERS: Brown; Ooijer, Samba, Nelson, Warnock; Emerton, Tugay, Olsen, Pedersen; Santa Cruz, Derbyshire.
Subs not used: Bunn, Mokoena, Villanueva, Fowler, Treacy, Roberts, Andrews.
Bookings: Pedersen, Samba
MANCHESTER UNITED: Van der Sar; Brown, Ferdinand, Vidic, Evra (O'Shea 71); Fletcher, Anderson, Giggs (Tevez 66); Rooney (Park 77), Ronaldo, Berbatov.
Subs not used: Amos, Nani, Rafael, Evans.