After a thrilling first leg in Spain, the blockbuster tie was right in the balance heading to Manchester. Barcelona struck first to edge ahead, as Alejandro Balde earned a penalty and Robert Lewandowski just about converted the spot-kick.
But United came flying out of the blocks after half-time and turned things around, Fred striking two minutes after the break before Antony’s brilliant first-time finish gave the hosts a 2-1 win at Old Trafford to book their place in Friday’s last-16 draw.
It extends United’s unbeaten run at Old Trafford in all competitions to 18 matches, and ensures they go into Sunday’s Carabao Cup final against Newcastle full of confidence, as they look to win the club’s first trophy since 2017.
United made a fast start to the second leg and should really have taken an early lead. Fernandes was played clean through in the opening minutes by Casemiro, but fired an effort straight at Marc-Andre ter Stegen.
That proved a costly miss, as Barcelona took their chance at the other end. Fernandes was involved in this too, adjudged to have pulled back Balde in what replays suggested was a harsh decision, and Lewandowski just about got enough on his penalty at the end of a stuttering run-up to beat David de Gea.
The likes of Marcus Rashford and Jadon Sancho barely had a touch, but it was a different story after half-time as Erik ten Hag’s side burst into life and swiftly levelled things up.
Fernandes fired the ball into Fred, who took a touch to control it and another to shin an effort into the bottom corner, the Brazilian caring not one bit about the contact.
Rashford went close and Antony had an effort saved from distance, as a rattled Barcelona struggled to cope with the intensity on the pitch and in the stands.
It always felt likely that if a winner did come it would be for the hosts and so it proved with just under 20 minutes remaining. Alejandro Garnacho and Fred had efforts blocked, but it was third time lucky as Antony fired a wonderful finish into the bottom corner.
Old Trafford erupted, Ten Hag’s side held on, and the United juggernaut marches on to Wembley.