Speaking on MUTV, the manager praised his players for remaining in top gear and extending the winning margin as last season's narrow title defeat to Manchester City continues to frustrate him.
"It was a pleasing part," said Sir Alex, of the conviction to keep going forward with the points safely in the bag.
"Last year, we lost the league on goal difference and it won't happen again.
"I thought the first half of the game never got started. Wigan were taking a minute for every goal-kick and slowed the game down. They kept possession well and are quite an aggressive team to play against, giving a lot of fouls away and stopping the game that way.
"Once we got the speed of the game right in the second half, it made a difference for us as we became more aggressive in terms of getting the ball back and making good tackles in midfield. That set a pattern with the crowd as it got them up. Scoring the first goal is always important in these type of matches and we ran out good winners."
Although disappointed with Javier Hernandez's early penalty that drew a comfortable save out of Ali Al-Habsi, Sir Alex was thrilled to see Paul Scholes grace another landmark appearance with a goal.
"It wasn't a great penalty," the boss confessed. "It can affect you a little bit in the sense you think you're having a good start but have to start again. We had a lot of strikes on goal in