Berbatov and Scholes scored a goal apiece to seal United's progress
Dimitar Berbatov knocked his former club Tottenham out of the FA Cup by scoring the winner at Old Trafford.
Roman Pavlyuchenko's header from Tom Huddlestone's cross put Spurs ahead, but they were pinned back after that.
Carlos Tevez was twice denied, first by Ben Alnwick's excellent save and later by the crossbar, before Paul Scholes equalised with a low, deflected shot.
Berbatov rifled in after latching on to Michael Carrick's superb lofted pass to seal United's place in the fifth round.
In midweek, Spurs came out on top after a terrific fightback at Burnley to reach the Carling Cup final - where they will meet United - but the Londoners were unable to repeat the trick.
United proved too slick, too strong and too incisive for their visitors, who seemed to surprise themselves when they drew first blood after only five minutes.
Pavlyuchenko beat Nemanja Vidic to Tom Huddlestone's cross and glanced a header into the far corner to give Spurs a dream start.
And it seemed a world away from the nightmare Spurs almost suffered against Burnley - a night boss Harry Redknapp called the most uncomfortable of his footballing life.
But Redknapp, who had selected a strong-looking line-up, was soon to feel discomfort again as United took control of the match.
United, too, were not as under-strength as expected, and it was familiar faces that were on the end of chance after chance.
Berbatov latched on to a ball over the top but dragged his shot wide and soon after, Tevez smashed a fierce effort against the bar.
It was not just experienced internationals who were catching the eye, United debutant Fabio Da Silva was making a big impact as an attacking left-back.
And the skilful Danny Welbeck was denied what would have been a Ricky Villa-esque goal by Chris Gunter's excellent block after the winger had weaved past three players.
Scholes and Cristiano Ronaldo shot off target as United peppered Tottenham's goal and Alnwick saved superbly when he palmed over a Tevez volley.
Yet after all their intricacy, it was an ugly goal that brought United level, when Scholes' low shot took a deflection off Huddlestone to leave Alnwick stranded.
But the strike that put United was top quality - and a double blow for Spurs as it involved two of their former players.
Carrick picked out Berbatov with a sublime pass and the Bulgarian took one touch to control before placing the ball into the bottom corner.
Spurs made a change at half-time, bringing on Giovani for the disappointing Luka Modric.
But while there was a little more threat from Redknapp's side there was no real cutting edge.
Gareth Bale shot wide from a tight angle and David Bentley, who later made way for Jermain Defoe, also struck a shot off target.
The former Blackburn winger's well-struck volley that whistled into the side netting was the closest his side came to an equaliser.
Ronaldo forced another good save from Alnwick but chances dried up as the tempo of the matched slowed.
Spurs tried to inject some pace into their play but never looked like getting an equaliser, despite applying some pressure at the end.
The Londoners had one handball appeal and one appeal for a foul turned down by the referee as United held on.
United will clinch an unprecedented quadruple if they win the Carling Cup, the FA Cup, the Premier League and the Champions League.
However, boss Sir Alex Ferguson will be concerned after Ronaldo, Da Silva and Welbeck became the latest additions to a lengthy injury list.
Manchester United manager Sir Alex Ferguson: "Give them a start - it always helps, doesn't it?
"But they recovered well, they played excellent stuff in the first half and the goalkeeper's made two or three very good saves, we hit the crossbar.
"Dimitar Berbatov's goal was fantastic but it was also a marvellous pass from Michael Carrick."
Tottenham boss Harry Redknapp:
"I thought we did well. It is tough to come here - you have to be careful, if you open up you can get beaten by four, five or six goals.
"We started well, but a bad two-minute spell cost us. In the second half neither keeper had an awful lot to do.
"But I thought we were always in the game and I could see us nicking a goal and earning a replay."
Man Utd: Foster, O'Shea, Neville, Vidic, Fabio Da Silva (Eckersley 53), Welbeck (Fletcher 86), Carrick, Scholes, Ronaldo (Tosic 72), Berbatov, Tevez.
Subs Not Used: Kuszczak, Giggs, Possebon, Chester.
Booked: Vidic, Tevez.
Goals: Scholes 35, Berbatov 36.
Tottenham: Alnwick, Gunter, Corluka, Dawson, Assou-Ekotto, Bentley (Defoe 72), Huddlestone, Zokora, Bale (Taarabt 67), Modric (Giovani 46), Pavlyuchenko.
Subs Not Used: Gomes, Gilberto, Rocha, Dervite.
Goals: Pavlyuchenko 5.
Ref: Peter Walton (Northamptonshire).
BBC Sport Player Rater man of the match: Man Utd's Carlos Tevez 8.30 (on 90 minutes).
Please note that you can still give the players marks out of 10 on BBC Sport's Player Rater after the match has finished.