The forward is stuck behind Romelu Lukaku and Alexis Sanchez in the pecking order at the Theatre of Dreams but no outfield player has featured more under Mourinho than Rashford since his appointment in 2016.
It had been reported on Wednesday that Rashford, although not happy with not being allowed to play through the middle, was not looking for a route out of Old Trafford.
The Manchester United striker revealed that he plans to retire from Belgium duty following the continental competition in two years' time after helping his nation to third place in the World Cup earlier this year. "He's a huge admirer of him, but he's got his job to do", Southgate maintained.
The England manager hopes that the intensification of the domestic season, with some clubs competing on three fronts as Europe fully kicks in next week, will mean that they get opportunities.
Manchester United striker Marcus Rashford is reportedly determined to stay and fight for his place at the club despite a lack of first-team football so far this season.
There have been questions about whether Mourinho fully trusts the young striker, but England boss Southgate has insisted that the young forward has the full support of his club manager. They have to try and win matches. "Is he going to fit in at Manchester United?".
It is not as straightforward for Pep as: 'Oh, I'll just give Phil a game.' Every decision you make as a manager has a knock-on effect and I understand how complicated that is. They are going to have the League Cup and European football, so there's more opportunity that the squads will get rotated. "He's got huge competition for places at his club, so you can understand (his frustration)".
A move to another club could provide more playing time but sticking at United will help him win silverware.
"Speaking about Marcus, I think I can expect that Sunday I'm going to be highly criticised for not playing him tomorrow, because some of the boys are really obsessed with me and some of them have a problem with some compulsive lies", said Mourinho.
Mourinho's side will be looking to end Watford's ideal start in the new campaign in a Premier League match set for Vicarage Road. "We have to remember that I don't think Harry Kane, at that age, had hardly played anywhere near the matches for Spurs, really".
Both of his goals were clinical strikes from inside the penalty area, where England coach Gareth Southgate has said he wants to see Rashford rather than stuck out wide.
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