Scott McTominay's eighth-minute goal means the Reds will now face Middlesbrough in round four, but the narrow win over Steven Gerrard's Villans was far from straightforward.
The visitors had two goals controversially disallowed via VAR, while United spurned a series of good situations throughout the game that could have helped us find a clinching second goal.
It made for a tense night at Old Trafford and for the interim manager, in particular. Afterwards, the German spoke to club media and gave his thoughts on the Reds' general performance, VAR's interventions, and the formation tweaks that he felt were key to securing victory.