However, Mourinho has revealed that the youngster is in line to feature against Southampton in the Premier League this weekend.
Speaking in a press conference on Friday, Mourinho said: “The opportunities will always come.
"Phil Jones was not playing. Lindelof got injured and Jones had the opportunity to play against Young Boys. It will happen all over the place I believe.
"For the other game Luke Shaw was suspended and now we have Ashley Young with four yellow cards. Who knows when the fifth is arriving? Players must be ready.
"In this case some are going away to the medical room and some are coming back. For example, this weekend will be the first call for Dalot. He is ready now.
"He had an important injury, surgery, then a second injury in the national team when he was coming up, when he was already playing against Young Boys and Derby County, when he was almost here.
"But now he has been training for two weeks and we think he is ready now.”
Dalot joined United from Portuguese giants Porto last summer with the defender brought in with the intention of being the club's right-back for a number of years.
Antonio Valencia and Ashley Young have filled in at right-back during Mourinho's United reign but the duo are both 33 and coming to the end of their careers.
United travel to Southampton looking to extend their unbeaten run with a performance to raise the mood around the club.
Mourinho's men drew 0-0 with Crystal Palace in their last league outing before unconvincingly beating Young Boys 1-0 on Tuesday.
Southampton, meanwhile, are similarly struggling for form under Mark Hughes with the Saints sitting 18th in the table, having won just one of their opening 13 games.