Argentina teenager Alejandro Garnacho came off the bench to score in stoppage time as Manchester United won 2-1 away to Fulham on Sunday.
It seemed the Cottagers had done enough to earn a point in the final Premier League match before the World Cup break.
But Garnacho's expert one-two with Christian Eriksen, in the last of three minutes of added-on time, finished with the 18-year-old racing into the box before producing a cool finish across Bernd Leno.
"He has a lot of talent and his work-rate together with the talent makes a big difference with us from the bench," United captain Bruno Fernandes told the BBC when asked about Garnacho.
"We are really happy for him and know he can give us goals, assists and prove the joy of football."
Eriksen had put the visitors in front in the 14th minute at Craven Cottage with his first goal for United as he finished off a counter-attack.
Former United striker Daniel James equalised for Fulham just after the hour, having only come on as a substitute for Harry Wilson minutes earlier.
"About time!," said Eriksen of his goal. "I owed a few so I'm happy to be on the scoresheet in the last game before the World Cup."
United remained fifth but this win meant they moved to within three points of fourth-placed Tottenham as Fulham stayed ninth.
Erik ten Hag's side arrived in London without several senior players, including Cristiano Ronaldo, Antony, Jadon Sancho and Raphael Varane.
Fulham were missing injured star striker Aleksandar Mitrovic but still made a bright start at Craven Cottage, with United goalkeeper David De Gea's early save denying Carlos Vinicius.
But it was United who broke the deadlock when Anthony Martial played in Fernandes, whose ball across the box left the unmarked Eriksen with a simple tap-in.
- 'Keep fighting' -
Fulham enjoyed plenty of possession and pressure but their failure to turn any of it into a goal was almost punished when Martial headed just over the bar from Luke Shaw's cross.
Eriksen also had a chance to make it 2-0 before half-time but fired wide.
Early in the second half, Fulham goalkeeper Leno denied Anthony Elanga in a one-on-one, before Antonee Robinson and Tim Ream combined to prevent Marcus Rashford scoring from the follow-up.
Having passed up those opportunities, United were pegged back in the 61st minute.
Willian's quick run down the left was well supported by the overlapping Tom Cairney, with his pass finding James as the substitute slotted hom from the centre of the box.
An emboldened Fulham pushed for the winner, with Joao Palhinha's improvised overhead kick forcing De Gea into a punched save.
But it was Garnacho, showing a composure belying his years, who had the final say.
"No words can explain what me and my team-mates feel in this moment," said Palhinha. "We are really disappointed with the result because I think we deserved to win this game."
But he added: "We will keep fighting and give our best for the rest of the season.
"Football is like this, sometimes the best team doesn't win."