At first glance, United had an uncomplicated task ahead in their clash against the Black Cats. David Moyes' side are bottom of the league having only managed 20 points all season.
The opening minutes saw the visitors hog the ball, and Sunderland unable to claim possession. However, clear chances were still missing when the hosts began to fight back creating some danger through Anichebe and Defoe.
Just as the home side looked at their best, the figure of Ibrahimovic peeled away from his marker to find the bottom corner to the Red Devils' relief.
Things went from bad to worse for the home side when Oviedo limped off injured and Larsson was sent off for a lunging challenge with his studs showing.
Forty-five seconds after the break, without a single Sunderland player getting a touch on the ball, Mkhitaryan beat Pickford with his low, left-footed shot, to seal the victory for Mourinho's team.
From then on the match went in one direction only, and Pogba with a lovely piece of skill found Rashford with a long ball, who played a little one-two with Ibrahimovic, and finished past the keeper.
The win at the Stadium of Light is a breath of fresh air for Mourinho, while Moyes' side look destined for relegation.