A week on from their deserved triumph at finalists Paris St Germain, United continued their 100 per cent start to Group H by securing a first home win of the season in some style.
Rashford was the hero in the French capital and was key again on Wednesday, netting a treble off the bench as Anthony Martial and Mason Greenwood also scored against Bundesliga leaders Leipzig.
It was a devastating attacking performance that means United look set to reach the knockout phase after just two matches of a tough-looking section.
The hosts went in at the break ahead through a fine, low strike from Greenwood but Julian Nagelsmann’s Leipzig looked threatening, leading Solskjaer to turn to his bench.
What a decision that proved to be. The video assistant referee gave the green light to Rashford’s first goal from fellow sub Bruno Fernandes’ pass, with the forward swiftly following that up with an impressive second.
Martial took the penalty he won as United ran amok, with star man Rashford wrapping things up and completing his hat-trick.