Sir Alex Ferguson believes Manchester United's six-goal humiliation at the hands of Manchester City was the wake-up call that his side so badly needed.
A first half goal from Javier Hernandez earned United a valuable away victory at Swansea City on Saturday as the newly promoted Welsh club suffered their first home defeat of the season.
The Swans had their chances, but Scott Sinclair's miss from barely half a dozen yards summed up a frustrating assignment for last season's Championship play-off winners.
No such frustration for United with Ferguson happy with a victory that keeps his side on the coat-tails of runaway leaders City.
"The game against Manchester City was a wake-up call for us," said Ferguson. "Over the years our defence has been an integral part of our success and I thought we did well in that area.
"Swansea are a good footballing side and they keep the ball well. Against a side like that, you have to be concentrating all the time and we need to get that concentration back in the team.
"A couple of weeks ago, there was a genuine criticism about our defending and the chances the opponents were getting.
"We had to make sure that we defended well and we did that apart from the miss when Michael Carrick slipped up. Having said that, I thought Michael was magnificent.
"Other than that slip, we were comfortable with our defending and for me, it's a good result in the context of how Swansea have been doing this season."
Swansea manager Brendan Rodgers said: "I was very proud of the players. I thought our second half showing against a team of that quality was outstanding. We were a little bit stand-offish in the first half and didn't quite press the ball how we wanted to press it.
"That meant Manchester United were too comfortable, although we had the chance to equalise. We said at half time that we needed to slightly reorganise and show a slightly different mentaility. We did that and began to how we have played all season.
"I thought the crowd were incredible and there is no doubt the players felt the occasion. I understand that.
"But the way they are playing at this level is absolutely fantastic. I thought in the end we deserved something."
Rodgers was in no way blaming Angel Rangel's slip and mis-cued pass for his side's defeat. Although Rangel gave away the ball to Giggs who found Hernandez at Michel Vorm's near post, Rodgers said: "The blame is on me because I ask them to play, I want them to play from the back. Maybe he was off balance a bit but we will learn from that and that's the important thing.
"I thought Ryan Giggs was outstanding although he is nearly as old as me. He put in a great cross and that was that. But no blame for Angel Rangel because he has been fantastic for me."
Sinclair's miss in the 22nd minute was Swansea's golden chance to pinch at least a point against a side that had previously never won in Swansea.
However, faced with an empty net, after a run and cross from Wayne Routledge, the former Chelsea winger fluffed his lines.
"Scott is disappointed that he didn't take the chance but I was delighted that he made up so much ground to get there," said Rodgers.
"He is upset by it because he would expect to have scored. But if he keeps getting in there he will score. I have told him that and I'm sure if he gets an opportunity like that again, he will score."