Manchester United held on to quell a spirited second-half comeback by Manchester City as they knocked the holders out of the FA Cup with a 3-2 third-round win at the Etihad Stadium.
United, who brought 37-year-old midfielder Paul Scholes out of retirement as a second-half substitute, seemed to be in control at the home of their local rivals after two first-half goals from Wayne Rooney, another from Danny Welbeck, and the sending-off of City captain Vincent Kompany.
But Premier League leaders City responded with an early second-half goal from Aleksandar Kolarov and, after Sergio Aguero struck with nearly half an hour remaining, the Blues appeared on the brink of a remarkable fightback.
Indeed, Kolarov nearly forced a replay in stoppage time when a stinging free-kick, from the edge of the area, was only parried by United goalkeeper Anders Lindegaard before being scrambled to safety.
"I think we made them [City] better than they were," Sir Alex Ferguson told ITV. "We were just so careless in the second half. At 3-0 up at half-time they thought they were through and took their foot off the peddle. It was a careless performance, we should have been home and dry."
City manager Roberto Mancini praised his team's character after going 3-0 down. "I am happy because I think we played a fantastic performance, the players did well in the second half. We scored two times, we had other chances to score in the end and we didn't concede any chances for them to score."
Ultimately, the tie was decided inside an explosive opening 12 minutes, during which United took the lead and City were reduced to ten men following Kompany's dismissal.
Rooney heads United in front
To make matters worse for City, they had enjoyed a commanding opening spell before the visitors scored with their first foray into the home half, a move started by Ryan Giggs' pass to Rooney.
The forward fed Antonio Valencia wide on the right before moving into the area and meeting the winger's cross with a spectacular header which went in via the underside of the bar.
And within two minutes City were left with even more of a mountain to climb after referee Chris Foy deemed Kompany's two-footed, sliding challenge on Nani warranted a red card.
It proved the defining moment of the game, even if City's initial response was impressive and featured a 20-yard curling shot from Aguero, which drew a superb, diving save from Lindegaard.
On the half-hour, United seemed to have taken a stranglehold on proceedings when Welbeck doubled the lead. Nani played an intelligent ball to the overlapping Patrice Evra, whose low cross eluded Welbeck only for Samir Nasri to inadvertently help it back into the path of the United forward, who volleyed home spectacularly.
After 38 minutes and another incisive Giggs pass, they stretched their lead further when Welbeck was tripped by Kolarov. Rooney took a poor penalty, which was saved by Costel Pantilimon, but responded quickly to the rebound and headed it into the open net.
City start comeback
Mancini brought on defenders Pablo Zabaleta and Stefan Savic at half-time, as part of a tactical reshuffle, and the move paid instant dividends when Evra brought down Micah Richards after 48 minutes. Kolarov then made it 3-1 with a spectacular 22-yard free-kick which beat the United wall and the dive of Lindegaard.
Nani headed wide and Rooney's latest long shot whistled past the post before Ferguson drew huge cheers from the visiting supporters by replacing Nani with Scholes just before the hour.
United felt they should have had a penalty when Kolarov tripped Valencia in the area but Foy was unmoved and soon afterwards City made it 3-2. Scholes was badly at fault for the goal, gifting the ball to James Milner deep in United territory.
Milner's right-wing cross found Aguero, whose initial shot was only parried by Lindegaard, and the City forward scored from the rebound. United attempted to take the sting out of City's recovery but lived dangerously when Phil Jones appeared to handle a Kolarov cross but escaped with only conceding a corner.