The Special One has been out of work since being sacked by the Red Devils at the end of last year.
Ole Gunnar Solskjaer replaced Mourinho at Old Trafford, with the Norwegian securing the job full time after impressing as interim boss.
United have already caused an upset in the Champions League this season, with the Red Devils coming from 2-0 down against PSG to progress on away goals (3-3 aggregate).
Messi will want to leave his footprint in a mythical stadium
Jose Mourinho
Solskjaer’s men face an even tougher task in the quarter-finals, with United facing Lionel Messi and Barcelona.
And while Mourinho admits it will be hard for United to stop Messi, the former Red Devils boss is confident his old side can cause an upset.
“United this season was capable to win against Juventus and against PSG why not to do it against Barcelona?” Mourinho told RT.
“Barca will be aware of that, will respect United and Old Trafford.
Man Utd news: Jose Mourinho says Lionel Messi is ready to shine at Old Trafford (Image: GETTY)
“Messi will want to leave his footprint in a mythical stadium.”
United are sweating on the fitness of Marcus Rashford ahead of the Barcelona showdown at Old Trafford on Wednesday night.
The England international has been struggling with an ankle injury.
However, Solskjaer says Rashford has taken part in training and he could start against Barcelona.
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