West Ham gained revenge for Sunday's Premier League defeat against Manchester United by knocking their hosts out of the Carabao Cup at Old Trafford.
Manuel Lanzini's ninth-minute effort, his first goal in almost 12 months and only his second since May 2019, proved enough to take David Moyes' men into the last 16.
Not even the second-half introductions of Bruno Fernandes and Mason Greenwood could swing the game the home side's way in a performance that exposed Ole Gunnar Solskjaer's pre-match chat about the strength of his squad as somewhat hollow.
Lanzini's goal was just reward for West Ham's flying start.