The United boss watched from the stands as a Wayne Rooney hat-trick and Ryan Giggs’ 100th Premier League goal ensured the Reds remain hot on the heels of Carlo Ancelotti's pace-setters.
The Reds survived a rocky first period before storming to victory after the break, and Sir Alex was pleased with the way his team remained calm before deservedly taking all three points.
“It’s a great result for us, 4-1 away from home, I was very pleased with that,” he told MUTV. “Some of the football was good, and in the second half we kept our discipline very well, we kept possession of the ball very well and we deserved it in the end.”
The Reds' emphatic victory negated a potentially lively debate about the award of Portsmouth's penalty, given for a slight shirt tug by Nemanja Vidic and subsequently converted by Kevin-Prince Boateng. Nevertheless, Sir Alex was satisfied by the manner in which his side overcame that setback.