The France international has not figured for the Blaugrana since March 13, when he was introduced off the bench during a meeting with Lyon at Camp Nou.
The 21-year-old had been nursing a hamstring complaint heading into that contest, but saw out a 20-minute cameo which included him finding the target in a 5-1 win.
That success booked Barcelona’s place in the last eight of Europe’s premier club competition.
It came at a price, though, with Ernesto Valverde conceding that his gamble on the fitness of a World Cup winner had backfired.
Dembele has not been seen since, with no further risks taken.
He is still to be given the green light to figure at Old Trafford on Wednesday, but will be making the trip to England.
Valverde has selected the Frenchman alongside the likes of Lionel Messi, Luis Suarez and Philippe Coutinho.
Barcelona had revealed prior to a 2-0 victory over Atletico Madrid on Saturday that they were reluctant to rush Dembele back.
Valverde ruled the exciting talent out of his plans for that fixture and suggested that he remained a doubt for a meeting with United.
The Blaugrana boss said: "He's definitely not available for [Atletico] and we'll see about Wednesday.
"It's not worth us taking the risk with the remaining games.
"I can say he will not be able to play [against Atletico]. Yesterday he trained for a little while with the group, we'll see if he does today, but he will be brought back into the group gradually."
That process appears to have been accelerated.
There has been no indication that Dembele will be included from the off against United, but he could form part of the matchday squad.
If he is considered to be ready for action, then he may be a useful impact option to have on the bench.
His pace and trickery would pose problems for any tired legs in the Red Devils’ ranks heading towards the closing stages of an eagerly-anticipated encounter.
Valverde will, however, be keen to avoid rushing the youngster back into action ahead of schedule and will be looking for his side to put in a performance at Old Trafford which requires no assistance from those not at 100 per cent.