Manchester United missed the opportunity to win their 13th FA Cup after losing 1-0 to Chelsea in the 2018 final at Wembley.
Phil Jones' mistake put the dangerous Eden Hazard clean through on 20 minutes leaving the defender no choice but to bring the Belgian down as he made a desperate attempt at a last-ditch tackle.
Referee Michael Oliver had no choice but to give the penalty and Hazard stepped up himself - sending David De Gea the wrong way with a composed spot-kick.
Jose Mourinho's men became more offensive after the break but struggled to prise open Chelsea's organised defence.