The Belgium midfielder remains suspended following his red card against Man City, but Eric Bailly's sending off in Thursday's Europa League semi-final second leg against Celta Vigo does not affect Premier League matters, therefore the Portuguese boss could stick with the Ivorian defender.
Even then, United - who have written to fans to say the likely allocation will be between 8,000 to 9,500 - expect to have far more applications than tickets.
BT Sport has exclusive coverage of Manchester United's Europa League final with Ajax.
United have three Premier League games left before they can fully focus on their seventh European final.
Considering the absentees and the fact Europa League glory offers silverware and Champions League qualification, Mourinho will again rotate with the final in mind.
Mourinho said: 'When the game was hard and they were better than us, and when we were in trouble and not playing well, it was that mentality, that desire, that togetherness that made the boys fight until the end. "They have 12 days to prepare".More news: North Korea fires unidentified projectile, reports say
More news: Die as WHO Declares Ebola Outbreak in Republic of Congo
More news: Melissa McCarthy's Sean Spicer Rage-Rolls Through NYC Streets
When asked if the result of the 24 May final in Stockholm would determine whether United's season was a success or failure, he said the media "have the right to say it and it makes sense to say it, but I don't feel like that".
"At half-time I told them how proud I was of them playing in such a way in this stadium and supporters".
Four minutes later, Lyon wasted their best chance to level the score, as Maxwel Cornet saw his shot off the post. We express ourselves through attacking football.
"Trophies are brilliant to lift and they go in the cabinet and add to a club's history".
Trips to Tottenham and Southampton are followed by Crystal Palace's visit to Old Trafford - a match that comes just three days before the Europa League final.
But Ajax, who finished with 10 men after Nick Viergever was sent off in the finale, held firm to reach their first European final since 1996 when they lost in the Champions League.