"Last season Theo Walcott was a surprise to us, he came in and was very important in crucial qualifying games," Capello told Gol Television. "This year our most improved player is Milner.
Related ArticlesCapello overlooks Ben FosterFabio Capello wary of confident SpainTriesman: Premier League don't call the shotsScudamore: FA must shape up after Watmore resignationBulgaria up first for England in Euro 2012Bobby Zamora strengthens World Cup case"He played with us three or four times and he will be part of the squad."
Capello also hailed Wayne Rooney's form this season and said the Manchester United's striker will be crucial for England this summer.
"Wayne Rooney has scored plenty of goals both for his club and country," he said. "He's been devastating all season and I can only hope he'll carry that form with him to South Africa.
"He is like a bull, he's strong, he started playing at 16 with Everton and now he's matured and ready for all the games."
On England's preparations, Capello added: "We are preparing very well.
"We have managed to find a very good site in South Africa and beforehand we are going to Austria to a place I know very well and have been to with Real Madrid and Roma - and for this I think that it will be a good build-up.
"But the most important thing is that our good players are physically well because they are the players who make the difference."