After eight straight group wins, Capello's team has qualified for next year's finals with two games to spare and he already has in his mind around 37 players he will consider for the squad which will eventually be slimmed down to the 23 allowed for the World Cup.
But Owen and King won't be in that final squad if their fitness keeps breaking down.
Because of persistent knee problems King plays only every other game for Tottenham while Capello made a late dash to see Owen start in the Champions League for Manchester United on Wednesday only for the striker, who has started only once for him in a friendly, to go off after 20 minutes with a recurring groin injury.
"I arrived at the last moment in Manchester to see him," Capello said. "The knee of Ledley King is another problem, for Tottenham, for (Spurs manager Harry) Redknapp, for me. If he's fit he's OK, he's one of the best centerbacks.
"When I select a player, I expect a player to play every game, not wait 10 days to play another game. He has to be fit, this is the problem, always, every game, every training, every day."
Capello will select his squad on Sunday for the final two group games away to Ukraine on October 10 and at home to Belarus four days later.
Although England is guaranteed to finish top of the group, the Italian wants his team to maintain its perfect qualifying run, cut out what he calls the "silly mistakes" in friendlies and has given himself a strenuous schedule of five Premier League games in three days from today to Tuesday to watch his players in action.
"We have to play with the same style and the same focus as in the other qualifying games. We have to improve with every game," he said. "I think it is important to stay together and speak about the silly mistakes that we made.
"I will speak with the defenders, I will speak with the group so that everyone will have to understand what happened and what we have to do to not make more mistakes."
With the likes of Jermain Defoe out with a broken hand and Joe Cole and Theo Walcott only just returning, Capello said he may field a newcomer in one of the next two games.
But he wants to keep as many of his regular squad together as possible to maintain its impressive qualifying form, and has told them not to take it easy against Ukraine and Belarus even though a place in South Africa has been assured.
"We have to play all the games with big confidence," he said. "We have to play like a team not to play with fear. We are England, we are one of the best teams in the world, we have to play every game to win.
"But we [must] respect the opponents, not be arrogant. If you play with arrogance it is impossible to win."
Capello is wary of the danger of Ukraine striker Andriy Shevchenko next weekend, and that's despite the former AC Milan and Chelsea star's lack of regular starts for his clubs.
"He always scores a goal against me. It's incredible," said Capello, who has also coached AC Milan, AS Roma and Juventus in Italy.
"He played the last 20 minutes here (in England's 2-1 victory), he scored again. Against Roma, against Juventus also. Hopefully he will have finished scoring before this game."
