Bruno Fernandes claimed Manchester United's fans made the difference at Old Trafford after Erik ten Hag's side dumped Barcelona out of the Europa League.
The Portugal midfielder gifted Barca a first-half penalty with a foul on Alejandro Balde, with Robert Lewandowski beating David de Gea from the spot. United fought back after the break, though, with Fred equalising and substitute Antony firing home the winner.
The result means Man Utd are still in contention for four trophies. They will take on Newcastle United at Wembley on Sunday in the final of the Carabao Cup, while they're also five points behind Premier League leaders Arsenal and have an FA Cup fifth round game on the horizon.
"As I’ve said they’ve [the fans] been with us in the toughest moments," Fernandes told BT Sport after the game. "This season we have been good, we’ve been really good, also because they are always behind us.
"This is something different, you can feel it between them and us, we have something special because they see that we are doing all we can to win games for them. Old Trafford was bouncing, that’s why we get the result.
Marcel Sabitzer completes Man Utd transfer after last-minute deadline day dash"When you get the goal straight after the second half starts you know they will be behind us. It was just a matter of time to score the second goal."
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Fernandes could have been the villain if United had failed to progress, but he didn't want to dwell on the early penalty decision. "Nothing I can say will change it now but I think it was too soft - both of us were trying to win the position," he said.
"Both of us using the hands, but it is what it is. I don’t want to make comments because after they will say I was disrespectful and I will be punished by that so they are always right, I can do nothing about that."
Ten Hag made the first of his substitutions at the break, bringing on Antony for Wout Weghorst and shuffling his front-line, and the change paid off when Fred scored within two minutes of the restart to make it 3-3 on aggregate. One more goal would do it for the hosts, and it was Antony himself who swept the ball into the far corner of Marc-Andre ter Stegen's net to clinch victory.
The draw for the last 16 will take place on Friday, with United unseeded after finishing as runners-up in their group behind Real Sociedad. They will face one of the eight group winners in the next round, though teams from the same country cannot be paired together so they will not be up against Premier League rivals Arsenal.