McClaren said: "From my point of view, Wayne Rooney has the potential to be a world-class player. He's still got a long way to go and a lot to learn but he has the potential to do that and he's a very important player for England.
It is more than three years since Rooney last scored a competitive goal for England and he accepts he has not done himself justice in an international shirt in recent years.
McClaren admired the striker's frankness and clearly hopes all the talk will bring rich rewards from the Rooney-Michael Owen double act today.
They will be up front together against Estonia at Wembley for the first time under McClaren, even though he has been in the job over a year. The England boss said: "I think the comments from Wayne were very honest and should be applauded.
"I'm all for players coming out with honest comments like that, and expressing disappointment in their performances.
"It's refreshing and there should be more of that. He's not making excuses.
"I would say that he's been a little unfortunate with England. He's missed squads because of injury and when he's come in he's just been getting back into form and fitness.
"But he should just continue what he's doing. He's still very inexperienced and very young.
"He's gone through some terrific experiences and he just has to keep performing at the level he's performing at since he's come back for United.
"We want him to prove it on the field - score goals, make goals, be the threat that Wayne Rooney is."
McClaren feels Rooney has put pressure on himself with the manner in which his career took off, resulting in a £30m move from Everton to United in 2004.
McClaren added: "The way he exploded on to the scene warranted the attention.
"To be fair, it's carried on. The move to Manchester United was a good club for him. He's learning and developing through them.
"He's got a lot of years ahead of him to become even better."