Capello has no concerns over Rio Ferdinand's recent errors but the 31-year-old's injury record at the start of the current campaign would put his ticket to the tournament in South Africa under threat if replicated at the end of the season.
Ferdinand had to wait until the end of October to play three consecutive United matches, straight after an international qualification double-header, but that run ended with him missing matches against Barnsley, Blackburn and CSKA Moscow.
He will miss the Barclays Premier League clash against Chelsea this weekend with a calf injury that could be related to a lower back complaint.
Capello's predecessors have made the mistake of taking semi-fit players to tournaments, but the Italian said: "The players with us in South Africa will be all fit. It's impossible to wait for one player. Little things are okay, but bigger problems and they will not be there.
"If you have to recover someone it's no good. When we go it will not be the warm season, when it is easier to recover. It will be cold in South Africa."
The fact Ledley King cannot play matches in quick succession has effectively ruled the Tottenham captain out of selection, despite his club form. Capello will be making sure his players are all fit to play consecutive matches before next year's tournament.
"If Rio will play the games before the last squad, for me he is fit and will go to the World Cup," he said.
"In that situation he can stay. We spoke about King and it is impossible for him to stay with us. Sometimes he trains Friday to play Saturday."
Capello's view on players being ready for consecutive matches means he will also monitor Portsmouth goalkeeper David James, who rests his knee after matches.
"He's playing well but his problem is he can't train for two days (after) each game," Capello said. "It's one problem we have to decide.
"I'm happy because (Ben) Foster played well, (Robert) Green plays well. And James has this problem and we have to decide what we'll do. I'm happy with the keepers, no problem."
Ferdinand is expected to miss next Saturday's friendly against Brazil in Doha but James is likely to be included in the squad to travel to Qatar.
Carlton Cole is injured but Capello has plenty of options in attack, meaning Michael Owen may miss out again - but the England boss is not closing the door on the Manchester United striker.
"He is in the provisional squad," Capello said.
Sunderland's Darren Bent may also miss out, although Capello added: "He's playing very well and scoring goals. He's improved a lot this year. Sometimes it's very important for a player to play."
Capello will be at Stamford Bridge to watch United face Chelsea, hoping his players stay fit enough to travel. One player he will be keeping an eye on is Joe Cole, who has recovered from a serious knee injury and was watched by general manager Franco Baldini in the draw against Atletico Madrid last Tuesday.
Kieran Gibbs will stay with the Under-21s, barring injuries to Ashley Cole or Wayne Bridge, but the Arsenal youngster has emerged as a contender for a back-up role.
"Gibbs is a really good player, he's very interesting for the future of the England team," Capello said. "But he's young and now he has to play in a really important game for the Under-21s against Portugal at Wembley."
Capello believes the Brazil friendly will be the test of how far his team have come.
"I think it will be important for us to understand where we are," he said.
"It is very important to note the different style that they play. Also we are playing against players at a very high level. This is very, very important. The same problems we will have to face at the World Cup.
"Brazil play like a team now, not waiting for a stroke of genius from one player."