Shearer says: "I hope there is not too much fatigue because there has been so much pressure put on him and rightly so by United this season. In every game he has come up with the goods.
Shearer, the former Newcastle and England striker, is a huge admirer of Ronaldo, who Portugal hope will be their inspiration when they start their campaign against Turkey in Group A in Geneva on Saturday.
He picks him as the player he would have loved most to partner up front during his career.
Can he be another Pele? Shearer says: "He has the potential. He has the ability, no doubt about that. He's at the best club to sustain it. But he's with Portugal whereas Pele was at Brazil and Maradona at Argentina. Whether Portugal have got the team, I don't know.
"I would have liked to have played with Ronaldo because he takes pressure away with other players trying to pick him up and tackle him. Not only that but it's his creativeness as well. I'm sure he would have made me some goals, although he wouldn't have taken the penalties. That's for sure. I might have let him have the free-kicks.
"The best strikers are the ones who score goals at the highest level and he's doing that. He can play anywhere, he's a great entertainer, you'll never tire of watching him play. It helps that he's playing in a great side at Manchester United but I'm looking forward to seeing him.
"He was very good at the World Cup but I think he has improved as a player and probably more importantly as a person since then."
Shearer disagrees with those who say Ronaldo must cut the showboating from his game.
He says: "When you pay your money you want to be entertained and he's an entertainer.
"There is probably an unwritten law in football that you don't take the mick but I don't think he has. It's just the ability he has got."
