Wilshere will start tonight against Brazil.
"I'm wary Jack is only 21," said the England manager.
"He had a fantastic debut two years ago and has missed a year of football, so I want to play down expectations, but you can't deny he is an exceptional talent.
"We saw a bit of him in Stockholm, but that was Jack just coming back. He'd only played a couple of games for Arsenal. Now we're seeing a player who's much more in tune."