The teenage forward replaced Mason Greenwood in the 76th minute of United's 0-0 draw with Real Sociedad at Old Trafford. As a result, he became the club's youngest ever player in a European match, at the age of 17 years and 23 days.
North London rival Arsenal on Thursday opened their fourth straight Europa League campaign with a 2-1 come-from-behind win at Rapid Vienna in an opening round of games affected by the coronavirus pandemic.