Portugal winger Cristiano Ronaldo is a major doubt for the World Cup quarter-final clash with England due to a thigh injury.

The Manchester United ace missed training on Friday, having previously featured with the rest of Luiz Felipe Scolari's squad on Wednesday.

Team spokesman Afonso Melo told Reuters that Ronaldo had been undergoing a private practice session, but admitted: "If he's not 100 per cent fit, Scolari won't play him."

Portugal captain Luis Figo had earlier admitted that Ronaldo would be a key figure in the clash with England, especially with Deco and Costinha absent due to suspension.

He said: "Cristiano is much better right now. He is an important player for us. I hope his performance will help us to do a great game.

"It is an important game for us and England. It is a great honour to be in this position right now.

"We haven't had the joy of reaching this point in a World Cup before."