Ole Gunnar Solskjaer claimed his Manchester United side "worked their nuts off" as they secured a stunning derby victory over Manchester City.
Bruno Fernandes and Luke Shaw struck early in each half as United ended the Premier League leaders' 21-match winning run in all competitions with a 2-0 success at the Etihad Stadium.
With City retaining an 11-point lead over United at the top of the table, the result may not change the outcome of the title race, but Solskjaer felt it underlined his side's continuing improvement.
The United manager said: "We knew we had to suffer out there. We suffered a lot. They worked their nuts off.
"I thought we started really brightly on the front foot. When you get that 1-0 lead it sets the tone for the game.
"I thought we were excellent for the first 10-15 and we settled into our shape. The second goal was incredible.
"We are going to do everything we can to keep the performance levels up every day.
"I feel we are a better team to 12, 16, 18 months ago. We have improved massively. We are more robust, resilient and there is more personality in the team. That is what I like."
Solskjaer hailed the performance of Shaw but admitted the left-back almost did not make the line-up.
The Norwegian said: "He was a massive doubt until after the warm-up. He needed to do the warm-up to be cleared to play.
"Luke's performance was top. He is aggressive, he is hard to play against one-on-one. When he goes forward on those runs he is unstoppable.
"He has improved so much and is improving all the time. I am delighted for him."
The only downside for United was the loss of Marcus Rashford in the second half with an ankle injury.
"We need to do a scan," Solskajaer said. "I've not had time to speak to the doctor yet."
City's loss was their first in 29 games stretching back to November.
Manager Pep Guardiola brushed off the setback and instead targeted the remaining victories his side need to claim their third title in four years.
He said: "What matters now is the next one in three days, Southampton.
"We are arriving in the important part of the season in the Premier League, 10 games left. Now is when everything is going to count.
"We have some points up front. We need six or seven victories to be champion and we are going to start with the next one.
"The margin is in our hands. We will come back with new fresh legs on Wednesday and try to do another game."
City were on the back foot from the moment they conceded a penalty with 34 seconds gone. Fernandes converted and, although Rodri hit the woodwork early in the second half, City were undone after Shaw doubled the lead on 50 minutes.
"Congratulations to Man United for the victory," said Guardiola. "They are so strong.
"After the first goal, for five to 10 minutes, we were a little bit out but after that we came back to the game.
"We played much better than the day against West Ham when maybe we didn't deserve three points and maybe today we played for more. But the result is the result. Congratulations. Next one."
Guardiola chose not to turn to record goalscorer Sergio Aguero as his side chased the game, leaving the Argentinian, whose season has been ravaged by injury and illness, on the bench.
"He could have played, maybe it was the wrong decision," Guardiola said. "I don't know."
