Martin Johnson warned Manu Tuilagi and Delon Armitage will have to keep their tempers in check if they are to stand any chance of playing for England at the Rugby World Cup.
Both players have been included in Johnson's 45-man training squad despite serving suspensions for high-profile incidents of violent conduct last season.
Johnson is confident both have the temperament to cope with a World Cup but said: "We can't have guys getting suspended down there for events on or off the field. We are in New Zealand. We all know what that is like, it is a goldfish bowl. And you are at the World Cup so you are in a goldfish bowl within a goldfish bowl."
He addded: "We need guys who are available to play. We don't need silly suspensions because it puts us all under pressure."
Tuilagi, whose four brothers played for their native Samoa, is in line to make his Test debut in one of England's August World Cup warm-up matches.
The 20-year-old is among a group of five centres in the 45-man squad, alongside Mike Tindall, Matt Banahan, Riki Flutey and Shontayne Hape.
England's 45-man squad included a return for Matt Stevens, six months after his drugs ban expired, and call-ups for the uncapped quartet Charlie Sharples, Mouritz Botha, Thomas Waldrom and Joe Simpson.