On-loan with Crystal Palace, Loftus-Cheek was judged man of the match on debut for England in their draw with Germany on Friday.
Southgate claimed after the final whistle that he has been such a threat that Chelsea‘s big names have been stalling his progress.
He said: “I’ve known Ruben a long time – I think the first time I saw him was an Under-16 international – I think Dele Alli played that night in his first game too.
“And when you see his physical size, you think you’ll also see a certain type of player. Then I saw what you all saw against Germany – one that is so technically-gifted.
“He’s also been able to battle through difficult spells at Chelsea where he’s been training with senior players who have recognised his talent and so they get to him in training.
“Have they kept him in his place? Yes. They probably saw the threat.”