The midfielder made his Three Lions bow in the goalless draw with Germany at Wembley and is set to get the chance to build on his man-of-the-match display when England welcome Brazil on Tuesday.
Asked how the 21-year-old had been in the days since his eye-catching debut, Southgate said: “Quiet, as usual!
“I think he obviously has taken a lot from the game, found it a great experience, that he was learning throughout it. It’s incredible really that he’s had so few 90-minute appearances in the league yet we’re bringing him into that sort of environment.
“We believe in him. He did really well. But sometimes the first game is easier because nobody is aware of you.”
The England manager also confirmed Tottenham’s Eric Dier will keep the captain’s armband for Tuesday’s friendly at Wembley.