The Red Devils secured a 1-0 away win at Sunderland to take another step towards the title, and the 71-year-old insists winning the Premier League is the club's top priority
The 71-year-old rested a number of key first-team players, including Rio Ferdinand and Wayne Rooney, for the trip to the Stadium of Light, which was decided by a first-half Titus Bramble own goal.
While the Red Devils are expected to field a strong side in Monday's FA Cup quarter-final replay against Chelsea at Stamford Bridge, the Scot claims winning the Premier League title is the club's priority, and in turn, the visit of the champions to Old Trafford a week on Monday.
"We have to win four games to get the title but the important thing is to focus on the next game which is Man City at home," Sir Alex told Sky Sports.
"I said before the game the players have galvanised themselves. The concentration & the focus [has been there] in every game and 25 wins out of 30 is a record and that’s down to the efforts of the players.
"It was an important win going into the Man City game with at least a 15-point lead."
The Red Devils boss also saluted his team's display at the Stadium of Light, the same ground where his side saw last season's title slip out of their hands, with his defence in particular coming in for praise.
"It was a battling performance by the players," he added. "We picked up two or three injuries and it was the courage that got us through in the second half I think.
"I think the concentration is much better than earlier season when we were losing goals. But we’re getting defenders back and that helps. A selection of two from five makes it much easier for us."
A Robin van Persie shot forced Bramble into the error for the own-goal, and despite his effort appearing to be heading wide, Sir Alex would like to see the strike awarded to the Dutchman, who has endured a barren spell of late.
"Scoring for Holland in the internationals helped him. Goalscorers are like that when they don’t score for two or three games and when they do score they get back in a stream," he added.
"They’re making a case for an own goal but I thought it was a wicked hit by him but it was a fantastic shot. I don’t know if it was going in or going wide but it would have been hard for any goalkeeper to handle."
David de Gea, who recovered from a knock to make a number of key saves, was also praised by his manager.
He beamed: "I thought we lost David De Gea for a moment. He was out for a few minutes but he got up and played a great part for us."