Paul Scholes and former Spurs favourite Dimitar Berbatov struck within a minute of each other to overturn Roman Pavlyuchenko's early opener for the Londoners.
• Redknapp rages at pundits
Berbatov will be particularly pleased with his goal given the brilliance of what turned out to be the matchwinner, although for Tottenham the true test of the week will come against Stoke on Tuesday while Sir Alex Ferguson's team tackle West Brom with Fabio and Danny Welbeck new doubts.
Injury concerns are relative. If Spurs boss Harry Redknapp was offered the opportunity of having the team Ferguson put out as his first-choice line-up, he would doubtless accept it without a second thought.
For United, it represented the best they could manage with 10 senior players missing, which just emphasised the folly of the Spurs board in believing theirs should be a top four team.
As Burnley had overturned a three-goal deficit to come within a couple of minutes of reaching the Carling Cup final at Tottenham's expense on Wednesday, it was hardly a surprise United should find acres of space in which to exhibit their skills.
Youngsters Fabio, on his debut, and Welbeck both impressed, while Carlos Tevez buzzed about in his usual enthusiastic style and Berbatov, so hated by the visiting fans, seemed to have all the time in the world, when as Tottenham know only too well, he needs very little.
Still, when Nemanja Vidic got himself in a muddle and allowed Pavlyuchenko to give him the slip and turn home a deft header, United must have been slightly concerned.
The trouble for Redknapp was his side still had 85 minutes to hold out.
Having survived a quarter-final pummelling to emerge victorious with eventual tournament winners Portsmouth on the same ground last term, he knew it could be done. But his present team are a pale shadow of the side he left on the south coast.
As the chances piled up, it was beyond imagination that Tottenham could survive. How cruel though that one of their old boys should wreak the havoc.
Michal Carrick's move north from White Hart Lane created none of the animosity Berbatov's did. In the same quiet way, Carrick has gone on to become one of the most influential members of Ferguson's squad.
When he spotted Scholes lurking with menace on the edge of the box, he coolly rolled a corner into the veteran's path. The shot was pretty fierce and once it had flicked off Tom Huddlestone, Ben Alnwick did not have a hope of keeping it out.
A minute later Carrick floated a pass over the Spurs defence. Berbatov's first-time control was awesome. His second touch was a precise shot into the bottom corner that again left Alnwick flailing.
In the blink of an eye, or two Carrick passes, the tie had been transformed. Not though United's injury woes as Fabio collapsed in agony in the early moments of the second period after he had landed awkwardly following an aerial duel with Spurs substitute Giovani dos Santos.
The young Brazilian hobbled off, almost certainly making it an entire team Ferguson will be missing at West Brom on Tuesday.
Fabio's replacement, Richard Eckersley, is a virtual mini-Scholes with his ginger hair. They were both born in Salford too.
United's next substitution heralded the exit of Cristiano Ronaldo, who headed straight for the dressing room after wishing Zoran Tosic the best of luck on his debut.
At the same time, Redknapp made the slightly odd decision to replace David Bentley, a player who at least possessed the confidence to shoot from distance, with Jermain Defoe.
Welbeck joined United's walking wounded late on and a late penalty shout was the best Spurs could muster.
Redknapp rages at punditsHarry Redknapp has accused TV pundits Andy Townsend and Terry Sheringham of
"jumping on a bandwagon'' after the pair slated Tottenham's performance at
Manchester United today.
Neither Townsend, nor former Tottenham favourite Sheringham, were impressed by
Spurs' efforts in the 2-1 FA Cup defeat at Manchester United, feeling they did
not try, especially once the hosts had gone in front just before half-time.
Following on from Redknapp's scathing criticism of his team in recent times, it
seemed like fair comment.
But Redknapp felt there was no need to attack his side's efforts this evening
and does not believe his TV critics were correct.
"That criticism is unfair,'' said Redknapp.
"I don't know what game they can have been watching. How can they say we
didn't try?
"I think people are jumping on a bandwagon. This is a tough place to come and
it is not like we have been beaten 6-1. We have lost 2-1.
"Everyone wants to jump on Tottenham at the moment. I was happy with the
effort today.''
Redknapp will assess his options ahead of Tuesday's encounter with Stoke, while
United boss Sir Alex Ferguson must also wrestle with a growing injury list after
adding teenage duo Fabio and Danny Welbeck to the men who are going to miss the
midweek trip to West Brom.
They were forced off today with calf and ankle injuries respectively.
"Cristiano has picked up a little bug as well,'' said Ferguson.
"We had to get the doctor to him this morning and I didn't think he was
anywhere near ready but he showed the appetite to play and it is always good to
have him on the pitch.
"He will be better by Tuesday. We could do without these things but Ryan Giggs and Darren Fletcher are fresh, so it is just the full-backs that are giving us concern.''
Manchester United 2 - 1 Tottenham Hotspur
