England's head coach revealed on Friday that he had felt the need this week to remind the Manchester United striker of the importance of staying on the pitch and avoiding a suspension that could be fatal to England's campaign.
"Rooney played all the qualification matches and he had no problem with the referee," Capello told a press conference on the eve of England's group C opener against the United States. I hope it will be the same Rooney in the World Cup. I spoke with him. He is a fantastic player because he wants to win and the hunger in him is really, really strong. But in this World Cup we have to be careful and respect the referees."
Concern over Rooney's temperament has been an ever-present theme for England since the striker was sent off in their quarter-final defeat by Portugal four years ago. The subject has been reignited by his booking for dissent in the squad's final warm-up match, against local club Platinum Stars here on Monday.
Capello admitted that Saturday's encounter with a resilient, well-organised United States side would test his players' nerve, but expressed confidence they were ready for the test.
"Usually the first game is hard because the expectation is really big, the pressure is big," the Italian said. "We stay here for many days. We have trained very well. I'm very happy because all the players are fit. I think they are really happy and OK at this moment, physically and mentally. Their minds are really focused on going forward in this competition."
The Italian has decided on his starting line-up but will not tell the players until two hours before the game, in keeping with his practice as a hugely successful coach of AC Milan, Roma, Real Madrid and Juventus.
"It means all the players are ready to play, in every moment physically and mentally. They are focused waiting (to know) which players will play. That is the reason I always wait until the last two hours." That will mean a stressful Saturday for Robert Green, Joe Hart and David James. The three goalkeepers all stand a chance of starting although Green, who has started in England's most recent competitive matches, is the favourite to get the nod.
The only thing Capello would confirm was that Gareth Barry, who has only been training for three days following his recovery from an ankle ligament injury, would start on the bench. That is expected to mean Joe Cole coming into the side with Steven Gerrard and Frank Lampard sharing defensive responsibilities in the centre of midfield.
Capello acknowledged that he had been enraged by some of England's lacklustre warm-up displays but said he could understand that players might be tentative in such matches because of the danger of getting injured on the eve of a tournament that, for most of them, will represent the pinnacle of their careers.
The head coach is expecting a different type of display on Saturday. "I want to see the spirit of the team, the English spirit that I saw during qualification," he said. "I also want to see them being really compact on the pitch. The challenge is to win. Everything else is words. We have to win, no more."