Wayne Rooney scored twice as Manchester United beat FA Cup holders Manchester City 3-2 in a dramatic third round tie at the Etihad Stadium on Sunday in which City played most of the match with 10 men after Vincent Kompany's early dismissal.
The Premier League title rivals' first meeting since City crushed United 6-1 at Old Trafford in October lived up to expectations with City fighting back after going 3-0 down, but ultimately failing to hold on to the trophy they won last May.
Chelsea, who won the cup three times in the four seasons before City's triumph last May, beat Portsmouth 4-0 at Stamford Bridge in a replay of the 2010 final which they won 1-0.
Juan Mata put Chelsea ahead just after halftime and three of Chelsea's goals came in the dying minutes with Ramires scoring twice and Frank Lampard once in stoppage time against the Championship (second division side).
All eyes were focused on the Etihad Stadium at lunchtime where City had been unbeaten since losing to Everton in Dec. 2010.
By halftime that record was in jeopardy with United 3-0 ahead and seemingly coasting into the fourth round.
Rooney headed them in front after 10 minutes, two minutes before City captain Kompany was controversially sent off for a challenge on Nani when he appeared to make fair contact with the ball, although referee Chris Foy ruled he had slid into the tackle with his feet off the ground.
Danny Welbeck scored with an acrobatic volley on the turn after 30 minutes to put United 2-0 ahead before Rooney made it 3-0 with another header, scoring on the rebound when Costel Pantilimon initially saved his penalty.
City stormed back after the break with Aleksandar Kolarov scoring from a freekick after 48 minutes.
Midfielder Paul Scholes, who came out of retirement on Sunday to rejoin United until the end of the season, came on as a 59th minute substitute but his loose pass enabled City to break for Sergio Aguero to make it 3-2 after 65 minutes and set up a dramatic finale.
Rooney told ITV: "We knew it was going to be a difficult game today. Obviously going 3-0 up, we maybe took our foot off the gas a little bit, City got two goals and we had to make sure we saw the game out which we managed to do so we are delighted."
Rooney dismissed any notion that he would be leaving the club following newspaper reports on Saturday morning which implied he had had a major falling out with manager Alex Ferguson.
NOTHING TO PROVE
Asked if he had a point to prove, Rooney replied: "Not at all: what's been in the press of late has been a load of nonsense, because it's me, because it's Manchester United, it's blown up out of context. There are no problems with me at this club, I want to be at this club for a long time."
Rooney said the team were surprised when they realised Scholes was in the squad.
"It was a bit of a shock to be honest, we didn't know until we were in the dressing room. It's great. It gave everyone a lift he's a fantastic player and he showed his quality when he came on."
United manager Alex Ferguson was not overly pleased with his team's performance despite victory.
"I think we made them look better than they were," he said, "We were very careless in the second half, but the problem was, being 3-0 up at halftime, the players thought they were through and took their foot off the pedal."