At a news conference at Old Trafford on Wednesday, it was suggested to Mourinho that Celta Vigo's motivation to win might be greater because they are the smaller club.
United take a 1-0 advantage into their Europa League semi-final second leg against Celta Vigo, and will progress to the Stockholm final if they prevent Vigo from scoring to set-up a clash against the victor of the other semi-final between Ajax and Lyon, with the Dutch side leading the tie 4-1 on aggregate.
Acceptance that a Premier League top-four finish is likely beyond United led to changes in Sunday's loss at rivals Arsenal, but the Portuguese is unapologetic. It doesn't matter what happened before, what matters most is the next one. If he is going to be a bit-part player at United then forget about it.
More accustomed to competing for Champions League titles, United are bidding to reach the final of Europe's second-tier competition for the first time in their history.
Mourinho has stated recently that he is prioritising the Europa League as their best bet to clinch a Champions League berth.
What TV channel is Manchester United vs Celta Vigo on?
The Red Devils go into the second-leg match at Old Trafford leading 1-0 after Marcus Rashford's late strike in Spain. "They deserve this game as a reward for their hard work and they deserve to play well and to put in a good performance".
United captain Wayne Rooney, the club's record scorer, did play against Arsenal and is fit to face Celta but his future looks uncertain after a frustrating and injury-hit season in which he has scored only seven goals.
"I see a difference between matches", said Mourinho.
While Rooney has started three of United's last four Premier League games with Zlatan Ibrahimovic out for the rest of the season, he was an unused sub in perhaps United's biggest game of the season to date; the first leg of their Europa League tie against Celta. That, together with their current travails in front of goal means that we expect Utd to continue their excellent defensive at home in this competition and ease through to the final. Asked how he would feel about winning the trophy in his first season, Mourinho said: "I'm not thinking about myself, I'm thinking about the club and players. It didn't annoy me; I understood that I couldn't play with them at that level".