Scott McTominay celebrated captaining Manchester United for the first time by scoring the only goal in a 1-0 FA Cup third-round victory against Watford on Saturday.
Ole Gunnar Solskjaer made nine changes to his team, who could go top of the Premier League on Tuesday, when they take on Burnley.
The home side started strongly at an empty Old Trafford, with Daniel James impressive on the left side of the attack, and were rewarded when McTominay gave them the lead in the fifth minute.
The Scotland international, who recently scored two early goals against Leeds, headed downwards from an Alex Telles corner and the ball went in off the post.
United were largely in control and Juan Mata saw an effort saved following a fluent team move and sumptuous flick by Donny van de Beek.
But McTominay’s header proved the only goal of a first half in which Watford threatened intermittently. Adam Masina’s effort was blocked by a mixture of United goalkeeper Dean Henderson and Axel Tuanzebe.
The opening period ended with United defender Eric Bailly being replaced by Harry Maguire after he was clattered by team-mate Henderson.
Solskjaer threw on Marcus Rashford and Anthony Martial midway through the second half but United were forced to settle for a 1-0 win.