Having drawn the first leg 0-0, United knew they would need to score twice should Sevilla find a way past David de Gea.
The two sides couldn’t be separated in the first hour but a quick-fire double from Wissam Ben Yedder turned the tie on its head.
Romelu Lukaku scored a late goal to give United a glimmer of hope for springing a sensational comeback but it proved nothing more than a consolation.
It means United’s only hope of a trophy lies in the FA Cup but Red Devils supporters were clearly frustrated with their team’s seemingly lack of desire against Sevilla.
And Spanish expert Balague has given a glum outlook on the future of Mourinho’s tenure at United.
“This is why many like me think Manchester United deserve much much much much more than this,” Balague tweeted.
“They have to play better. Propose more football when you spend so much.
“Old Trafford and United fans deserve so much more.
“Today might have been the end of an era (even if nothing changes).”
United will aim to pick themselves up for their FA Cup quarter-final clash against Brighton on Saturday (7.45pm).