Anthony Martial snatched a last-gasp winner to send Louis van Gaal's Manchester United into a potentially season-redeeming FA Cup final as the favourites following a 2-1 victory over Everton at Wembley.
With the semi-final headed for extra-time after a 75th-minute Chris Smalling own goal had cancelled out Marouane Fellaini's first-half strike for United against his former club, Martial was on target in injury time.
Everton, with manager Roberto Martinez under fire and out of favour with the fans, could have levelled in the 57th minute when Timothy Fosu-Mensah felled Ross Barkley but David de Gea's superb diving save denied Romelu Lukaku from the penalty spot.
United, who will face Watford or Crystal Palace in the final, had their own penalty appeal turned down nine minutes later when Fellaini's shot was blocked by Phil Jagielka's arm.
Dutchman Van Gaal has faced endless debate about his United future, with media speculation that Jose Mourinho is waiting in the wings, after crashing out of Europe and poor performances in the Premier League.
The final, with United on course to lift the trophy for the first time since 2004, would be a silver lining even if there are no guarantees he will still be in the job next season.