Matthijs de Ligt scored his first goal for Manchester United as Erik ten Hag's side claimed a much-needed Premier League victory at Southampton.
The Red Devils went into the recent international break on a low after being comprehensively beaten by Liverpool, and needed to put in a performance on their return to action.
They survived a difficult start before a penalty save by Andre Onana from Cameron Archer proved the turning point as soon after they took the lead.
Summer signing De Ligt got the opener, heading into the bottom corner from Bruno Fernandes' fantastic ball into the box.
Six minutes later Manchester United doubled their lead, Marcus Rashford opening his account for the season with his first goal since March, guiding a low strike through a crowd into the net.
The double blow seemed to quell Southampton's eagerness and Manchester United were comfortable in the second half.
A bad day was rounded off for Southampton when Jack Stephens was shown a straight red card late on for a reckless challenge on Alejandro Garnacho.
The substitute then wrapped up the win for the visitors with a thumping finish into the roof of the net deep into stoppage time.