Everton manager David Moyes has hailed the improvement made by Marouane Fellaini since he signed the Belgian in 2008.
The 23-year-old, who is the club's record purchase, has received a number of plaudits for his performances so far this season and Moyes believes that the former Standard Liege player can progress further.
"I've said all along I think Fellaini is a really good player in the Premier League," Moyes told the club's official website.
"And he's young. He's only 23 now so you think what he could be like when he's 26 or 27.
"But we think he's already come on a lot. He's physically stronger, much more disciplined in the job he has to do in the team."
Fellaini recently signed a new contract at Goodison Park.