The Italian, who will name his squad later on Sunday for next Saturday's friendly against Brazil in Doha, said the rule applied to every player including Manchester United's Ferdinand, who he described as one of the best centre-backs in the world.
Both Ferdinand and James have missed matches recently because of injuries and unlike England coaches of the past, Capello said he would not consider taking anyone with an injury that might even heal during the month-long competition.
"The players that will be with us in South Africa will be all fit," Capello said. "If you go to South Africa and try to recover there, it will be no good.
"It will not be warm which makes it easier to recover. It will be cold in South Africa for the World Cup.
"It's impossible to wait for a player. Little injuries, okay, but anyone suffering bigger problems, they will not be there.
"Rio is absolutely one of the best centre-backs in the world. As a player I have no worries about him. But he needs to be really fit and playing every game.
"Right now he has some problems with his back and he has to train more."
Former England manager Sven Goran Eriksson included David Beckham in the 2002 squad and Wayne Rooney in 2006 when both were recovering from broken bones in their feet, but Capello will not tolerate the same leniency next year.
NO KING
For that reason, Tottenham Hotspur captain Ledley King, who is battling a long-term knee injury and only trains once a week, will not go to the World Cup and a doubt remains over James, England's first choice goalkeeper.
"We have spoken about King and it is impossible for him to come with us," Capello said. "He trains only on a Friday to play on a Saturday.
"We are following David James. He's playing well but his problem is he can't train two days running. It's a problem we have to decide, but we have time.
"But I am not worried about the goalkeepers, we have Robert Green, we have Ben Foster, but James has a problem."
Capello added that next week's match against Brazil will act as a good barometer as he begins to fine-tune his preparations for the finals.
"The match will be important for us to understand where we are. We will be against players who are at a really high level.
"They will pose the sort of problems we will have to face at the World Cup."
Not surprisingly, he ranked Brazil as one of the favourites in South Africa.
"When they started their qualification they had some problems but step by step they have improved.
"They are strong, defending well and really dangerous with their forwards and their movement without the ball.
They play like a team now, not waiting for a stroke of genius from one player ...and it will be a great test for us."
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