When the teenager replaced Academy graduate Mason Greenwood in the 76th minute, he became the club's youngest ever player in a European match, at the age of 17 years and 23 days.
The previous record holder was Norman Whiteside, who was 108 days older than Shoretire when he played in a continental fixture for the first time.
Curiously, the competition, venue, scoreline and nationality of the opponents, Spanish, were all the same. United drew 0-0 at home to Valencia in the UEFA Cup, the Europa League's former guise, when Whiteside made his debut in Europe, on 15 September 1982.