Gerrard: Players warned by Capello over discipline

England's players have been warned by coach Fabio Capello about the importance of controlling their aggression at the World Cup, captain Steven Gerrard said Thursday.

The need for discipline in Saturday's opening match against the United States was highlighted Monday when striker Wayne Rooney was booked in a training game after swearing at the referee.

The Brazilian referee and his assistants who will take charge of the Group C opener also told Brazilian media they have been studying English-language obscenities the players might hurl at them.

"In this day and age I think it's important to show the referees some respect," Gerrard said. "You don't use any language because then you'll be booked and the whole team suffers. You don't want to fall into that trap ...

"We've had experience of losing big players at important times."

That happened four years ago when Rooney was sent off for stamping on a Portugal player in the World Cup quarterfinals, which England went on to lose on penalties.

"Wayne's experienced enough now to deal with it," Gerrard said. "Wayne understands we need him on the pitch, he's a very important player, and every player has been warned by the manager and coaching staff to channel their frustration in the right way and not get involved with the referees or with any silly challenges."

At the same time, though, Gerrard said England's chances would suffer if the 24-year-old Rooney's passion on the pitch was curbed.

"He is a fantastic player and we don't want to take Wayne's fire away from him because that's the type of player he is, always on the edge," Gerrard said. "That is the reason he is one of the best players in the world. Wayne himself just has to make sure he controls his frustrations in the right manner - and takes it out on the oppositions and not the referees."

Rooney, who scored 35 goals for Manchester United last season, is certain to feature in the starting lineup Capello has finally settled on to face the Americans.

"I know the 11 that will play Saturday and I hope the next two days, during the training, all the players will be fit," Capello said. "They've improved a lot. We found a spirit and different systems to play during the game."