After joking that he would take United's penalty following the Reds' fourth spot-kick miss of the season, the manager took time out to praise his side's opening goalscorer Robin van Persie.
"It was good for Robin to get the goal and he took it very well," said Sir Alex. "I thought he was fantastic today - his movement and his penetration were brilliant.
"He did the right thing [not celebrating his goal]. He had eight great years at Arsenal and he respects that and I thought the Arsenal fans were fine too."