Just days after signing a permanent deal, emergency striker David Bentley got his first professional hat-trick.
Lucas Neill's penalty on the stroke of half-time had given Rovers a 3-1 lead, with Louis Saha's equaliser and Ruud van Nistelrooy's second-half double proving too little too late.
Fresh from his brace against Wolves at the weekend, Kieran Richardson went close early on with two efforts in the opening three minutes. But in a first half disrupted by Phil Dowd's whistle, it was Rovers who struck first.
Following a foul on Shefki Kuqi on 35 minutes, Morten Gamst Pedersen's brilliant free-kick was superbly tipped on to a post by Edwin Van der Sar, but Bentley was there to steer the ball through the keeper's legs from close range.
Their lead didn't last long however, as just two minutes later United were level. After a corner from the right was only partially cleared, Wayne Rooney fired the ball goalwards and, as Brad Friedel parried, Saha acrobatically scored the equaliser on the rebound.
But as the half drew to a close, more goals followed. On 41 minutes, following a mix-up in defence between central midfielder Rio Ferdinand and Van der Sar, Bentley was presented with the easiest of goal-line tap-ins for his second.
And in time added on United handed Mark Hughes' side another gift. Steven Reid's ball-in was handled by Wes Brown and Neill calmly slotted home from the spot.
Tugay was sacrificed for Brett Emerton at half-time, but it didn't do anything to halt Rovers' rampage.
On 56 minutes, Robbie Savage flicked the ball over the defence to Bentley and, with time and space, the former England Under-21 international buried his fourth goal in two games with a crisp right-foot volley.
But the double substitution of Ji-Sung Park and Van Nistelrooy a minute earlier brought double reward for Alex Ferguson's side on 63 minutes.
Cristiano Ronaldo capitalised on some sloppy defending by Andy Todd to present Van Nistelrooy with his first and, just five minutes later, after Patrice Evra's pass had been flicked on by Brown, the Dutchman blasted home his second.
As the clock ticked down Ferdinand was shown a red card following successive fouls on Pedersen and Savage, as Rovers held out for another famous win.