Southgate has expressed concerns that Rashford is not starting enough games for United and the 20-year-old’s minutes on the pitch have decreased following the arrival of Alexis Sanchez in January to improve Mourinho’s attacking options.
Rashford has made 38 appearances – the joint second highest of any United player this season – but Southgate’s concern is that only 20 of them have been starts, with the other 18 as a substitute.
And the bigger worry for Southgate is that since Rashford’s last Premier League start on Boxing Day, he has played only 311 minutes of football, and just 128 of those in the League.
But Mourinho, who met the England boss for talks at United’s Carrington training ground on Friday, insists Rahsford’s involvement is more than enough to clinch his passage to Russia – if Southgate continues to believe in him.
Asked if he had given re-assurances to Rashford, Mourinho said: “No, I don’t reassure anyone. The main reassurance for him is that he is always selected. There is not one single match when Marcus is not selected to start or to be on the bench.
“I see people sometimes putting doubt over whether he is going to be selected or not for the World Cup but if the national coach trusts him, he selects him.
“It doesn’t matter if he plays for us or doesn’t play. There are many examples of players who don’t play for their clubs at all and they still go to the national teams.
“You have the example of Sergio Romero, who is the second goalkeeper at Manchester United and the first goalkeeper for such an amazing football country like Argentina.
“In your own country [England], you have examples of players who play even without scoring a goal in the Premier League. So it’s up to Gareth Southgate. If he trusts him, he selects him. It doesn’t matter if he plays or if he doesn’t play for Manchester United.”
Despite his limited start-time, Mourinho says he is happy with the progress Rashford has made since he burst on the scene with a flurry of goals under Louis Van Gal two years ago.
And he says Rashford’s ‘feet on the ground’ demeanour will serve him well in the future and is the same as another academy graduate, Scott McTominay, who has made the breakthrough this season.
As United prepared for tonight’s visit to Crystal Palace, Mourinho added: “At his age, what Marcus is doing is more than enough and the experience he’s getting at every level is more than enough for us to be happy with what we think is going to be his future. It’s as simple as that.
“But because he had such an impact at the beginning, probably people expect him to play even more than he does, and score even more than he does and perform even more than what he does but it is not so simple.
“What I see makes me really happy, to see the same boy. When you ask me about Scott McTominay, I spoke about McTominay as a boy before he was a player and Marcus is the same.
“What will keep them both in the right direction, what will make them have that stability to improve is what they are as boys. And Marcus is a fantastic boy, also very grounded. For sure, we love him and we believe in him, and he’s going to have the chances.”
What Palace boss Roy Hodgson is worried about is not so much the boys but the man who has already tormented his defence this season.
Sanchez has previous at Selhurst Park, scoring twice to help secure Arsenal’s 3-2 win just before the turn of the year.
The striker returns tonight with his new club searching for a return to scoring form after netting just once in seven appearances for United – his only goal since that December double.
Hodgson knows the Chile striker still poses a major threat as Palace attempt to haul themselves back out of the bottom three at the start of a month that also sees them face Chelsea and Liverpool.
“We are going to be playing against a very good player and if we give him a lot of time and space, and if we give him a lot of opportunities to do the things he is good at, he is likely to succeed,” said Hodgson.
