It was a completely different story after the break as the game came alive. Villa opened the scoring shortly after half-time, with Ollie Watkins calmly finishing past debutant Dubravka.
United equalised within a minute as Martial grabbed a goal on his comeback. Villa again took the lead just after the hour mark when Diogo Dalot was forced to put into his own goal.
But the Red Devils again fought back, with Marcus Rashford this time finishing well from close range. United were buoyant and capitalised on a poor pass out from the back from Olsen to go into the lead for the first time.
Bruno Fernandes took advantage and saw his deflected effort go past the Swede, before Scott McTominay sealed the win in stoppage time. United ran out 4-2 winners and proved Schmeichel wrong with his half-time comments.
Want the latest Premier League news as we publish it on Express Sport? Join our new Facebook group by clicking here