Martial was getting more opportunities in the starting eleven before Sanchez joined in January, but Mourinho refused to provide any indicators over the Frenchman's future at the club.
United host West Brom at Old Trafford on Sunday, looking to cement their grip on second place in the table.
Both players could arguably do with a run in side to play themselves into form.
"So I think you are playing not only for yourself and for the club, but for all the people that are living that dream through you".
Mourinho also confirmed that Rashford is the only player who have made the most appearance since the Portuguese manager arrived at the club.
And during a press conference on Friday, Mourinho was asked if it is hard to keep all of his players happy. We can not have 11 players - it would be incredible, also economically for the football clubs - to have only 11 players and play always with the same 11 and no injuries or suspensions or fatigue and nothing, it would be better for everyone but it is not possible.
"So in every club, at every level, from the top of the world to the amateur football clubs, you need more than 11 players and only 11 can start, is as simple as that, there's nothing I can do".
The 22-year-old France global forward, who cost the Red Devils an initial transfer fee of £36 million when they signed him from AS Monaco in the summer of 2015 according to BBC Sport, is one of the best young players in Europe, and there is no doubt over his quality.
United rode on a sublime second-half performance by French midfielder Paul Pogba to seal a memorable 3-2 victory at the Etihad Stadium but Mourinho said subsequent training sessions were spent in getting his players to move on from that win. If United can cut loose more often, fans and media may not grumble as much about the personnel.