Sir Alex Ferguson praised Manchester United's "ghost" for raising their spirits in the Barclays Premier League title race.
Veteran midfielder Paul Scholes celebrated the signing of a one-year extension to his contract with a dramatic winner in the derby against Manchester City.
Three minutes into stoppage time he got on the end of a cross from Patrice Evra to flick a header beyond goalkeeper Shay Given.
With Scholes rolling back the years, United are still in with a chance of a record fourth successive title.
Ferguson said: "It was an amazing finish. We have three last-minute goals against them now (this season) but deserve it.
"We had the best chances but it did not look like anyone was going to win. The game became very open in the last 10 minutes.
"That gave us the chance to get players forward and there is none better at that than Scholes. I'd almost given up and thought it would be 0-0.
"You know with us it's happened so many times we score late and you always hope it will happen again.
"I decided to put Scholes a bit further forward and it paid off.
"No-one is better than him at ghosting into the box. There was no-one near him and it was a free header.
"He was man of the match today, he was wonderful, he's such a skilful player."
Scholes said: "I think we were the team pressing to try to score and fortunately we were lucky enough to win the game with not much time left.
"It's nice to win any game against City, and away from home especially."
With Wayne Rooney back after an ankle injury United carved out a number of chances but were unable to convert any of them until Scholes struck.
The England striker looked frustrated and was replaced in the second half by Dimitar Berbatov. That came shortly after he was left rolling on the floor following a challenge from Vincent Kompany, which saw the City player booked.
Rooney suddenly recovered, then raced away and Ferguson said: "I asked him why he got up.
"He said it was because he thought Kompany was getting sent off so he jumped up. Then the crowd booed. It's a cruel world."
Ferguson added: "We wanted to keep a clean sheet because we know if we get back to zero against it gives us a chance. One-nil wins have played a big part in our title wins and 1-0 today shows that's true.
"Derbies are derbies and the way we have won has given our supporters great excitement. To do it that way on City's own ground is a great result for us."