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.
"Yes he is (a special talent)", Southgate said of Rashford after seeing him score the only goal in Tuesday's friendly win over Switzerland.
He's Marcus Rashford, Manchester United player, with an incredible number of appearances and an incredible number of minutes played at the highest level in the best possible competitions. "There is huge competition for places at his club so you can understand that". He had left [Riyad] Mahrez out of the team, so he needed to get him on because he [Mahrez] is still adapting to the way of playing.
"I understand the difficulties that club managers have".
Gareth Southgate has warned his England players that it will be hard to pick them for next month's Nations League games in Croatia and Spain if they are not playing regularly for their clubs.
The Mirror has reported that following the victory over Switzerland, Southgate suggested Rashford's performances for England would boost his confidence and emphasised that he was still an emerging player with world-class potential. They have to try and win matches. "He ended up top scorer and then got his move to Manchester United". "We have to remember that I don't think Harry Kane, at that age, had hardly played anywhere near the matches for Spurs, really".
"But the media is very important and it is very important Manchester United supporters know the truth, that's why I'm going so specific about these numbers".
Despite Rashford's frustration with a lack of starts at United, Southgate said his club manager Jose Mourinho was a huge fan. "For me, I was delighted because we really wanted to make him feel important over this period anyway".
"Even with some of the step-overs and things Ronaldo was doing at that age he wasn't converting them into the number of goals". They are going to have the League Cup and European football, so there's more opportunity that the squads will get rotated.
He will serve the first game of a three-match suspension when United travel to face Watford on Saturday evening.