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.
Both Alan Shearer and Jamie Carragher have argued that Rashford will not get enough minutes as a central striker with Romelu Lukaku leading the line at Old Trafford.
Rashford starred for England over the worldwide break, netting for England in games against Spain and Switzerland.
The 20-year-old has started just one game for United so far this season and will miss the next three through suspension following his red card in the 2-0 win over Burnley last time out.
"Yes he is (a special talent)", Southgate said of Rashford after seeing him score the only goal in Tuesday's friendly win over Switzerland. Chelsea midfielder Ruben Loftus-Cheek, another starter against Swtizerland, kept his place in the England squad despite not starting any of the Blues' opening four league games this season.
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.
"For me, it's the biggest club in the world, and I think he's got the potential to be one of the best".
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 have a hard job to do and they have big squads in the top six, with huge competition for places.
"We really wanted to make Marcus feel important over this period", said Southgate, according to Sky Sports.
"It's not my business to interfere with club managers, they have a hard job to do and they have big squads at the top six, huge competition for places, so Jose thinks the world of Marcus", Southgate said. "They have to rotate their squads".
"His confidence will be boosted with two goals against top-quality opposition".