The 19-year-old Portuguese defender Dalot came on as a substitute in last Saturday’s 2-2 draw at Southampton.
He started a Champions League match in September against Young Boys in Switzerland and the home Carabao Cup game against Derby County but this is his first appearance in the XI for a league fixture.
Back from injury for United to face the Gunners are Chris Smalling and Eric Bailly, who both missed the game at St Mary’s. Matteo Darmian also returns and there is a first senior game of the season for Marcos Rojo, who has only previously appeared as a guest player for the Under-23s this term.