The 24-year-old missed Saturday's 2-1 win against bitter rivals Liverpool with an injury sustained on the eve of the game.
United take on Sevilla at Old Trafford this evening needing to win to book their place in the quarter-finals of Europe's elite competition.
But as the Champions League enters the knockout stages, only 12 teams remain and the quarterfinal of any cup competition is the point at which teams start to believe they can go all the way.
With Manchester City proving uncatchable, finishing in the top four is United's only realistic aim in the Premier League. Or is he just goading Liverpool?
And Red Devils playmaker Mata has talked up the importance of not underestimating their Spanish opponents in the return leg of their Champions League tie on Tuesday night at Old Trafford.
But he says that the "most important match" he has overseen was May's Europa League final victory over Ajax, which completed the club's set of European trophies, and assured Champions League qualification. "Not yet, but when a team reaches the last eight anything is possible", Mourinho said.
United boss Jose Mourinho faces the media later in the day and is sure to be asked about the midfielder's availability - something he was unsure of after beating Liverpool.
"He was saying that it's not good for Marcus Rashford to have a coach like me because the most important thing for me is to win. We are going to try to show we are better but I don't feel we have any advantage", Mourinho added.