BUEHLERTAL, Germany _ Rio Ferdinand secretly doubted when it came to Wayne Rooney's fitness level at the start of the World Cup.

"Even when I spoke to you guys and said 'Yeah he'll be all right, he'll be fit,' I had quite a bit of doubt in my mind that he'd be fit and ready," Ferdinand told reporters Tuesday. "He's naturally a fit lad and ... he's naturally a good footballer so it's not like he's going to lose his touch overnight."

Rooney sat out England's first match, but came on as a substitute in the second and started the last two. He played the full 90 minutes against Ecuador in the second round.

"But we don't want to go overboard and say he's back to his maximum," added Ferdinand, a teammate of Rooney at Manchester United as well.

Rooney broke a bone in his right foot on April 29. Since he started playing again in Germany, his form has improved and he has provided a spark for a team that has not played its best soccer at this year's World Cup.

But the 20-year-old Rooney playing at all was a surprise to most. Maybe his dedication to the game helped.

"People talk about the way he looks and stuff sometimes, but Wazza probably does the most running in the United team throughout the season and it's probably the same with England," Ferdinand said.

Rooney played as a sole striker in England's second round win. He might be paired with Peter Crouch for Saturday's quarterfinal match against Portugal, but Ferdinand doesn't think it matters where he plays.

"Wayne can play the man off the front man or the man up front on his own," Ferdinand said. "He's that good and I think he's got enough strength and desire and nouse to do that. He can run in behind as good as most center forwards or he can drop off, he's that good."