With United 1-0 down beyond 80 minutes, the 22-year-old stepped up to the plate and grabbed the game by the scruff of the neck in just 12 second-half minutes to rescue Ruben Amorim's side.
His first game with a bit of perseverance after driving into the box and finishing at the second attempt and his second – in the 90th minute – was well-taken after a lovely exchange with Christian Eriksen.
Amad completed his wonderful hat-trick a few minutes later after seizing on a defensive lapse from Southampton to cap off a determined and mature display.
United and Amad will be hoping for more of the same on Sunday when they welcome Brighton to Old Trafford in the Premier League.