The players aren't the only participants who understand that a bad decision at a crucial juncture of a game could end their participation in the 15th World Cup.
Referees have handed out yellow cards at a record rate, and it seems as if they've received just as many warnings from FIFA, which has been promoting tighter officiating all year.
"One call could either keep you here, or send you home," said Paul Tamberino, a Baltimorean who's among the premier soccer officials in the United States. "That has to weigh on a referee's mind. At this stage, the officials are just like the players. Each time out, you've got to make improvements."
Tamberino, 40, was one of four men the U.S. Soccer Federation nominated to officiate in the World Cup. Only one of the four, Arturo Angeles, a referee from California, was selected by FIFA for the pool of 46 officials.
So Tamberino has been attending games as a fan. While the majority of spectators at the four group games at RFK Stadium in Washington marveled at Saudi Arabia's Saeed Owairan or Mexican goalkeeper Jorge Campos, Tamberino found himself following the men with the whistles and flags.
"To be honest, I watch more of the referee than anyone else," said Tamberino, who excelled as a player at Archbishop Curley High, Essex Community College and the University of Maryland before turning to officiating 17 years ago. "I want to see their position in correlation to the flow of the game."
Tamberino called Arturo Brizio "one of the best in the world," the same day the Mexican referee was sent home after the Italy-Nigeria match in which he made a controversial ejection. The day before, referee Kurt Roethlisberger was dismissed for admitting he missed a call on a German foul in the penalty area that would have given Belgium a chance at a tying penalty kick.
"The Swiss referee made bad calls," said Viken Djizmedjian, a FIFA media spokesman. "All referees are given grades after the game. Those who don't referee very efficiently are sent home after the first- or second-round games. As there are fewer games, we keep only the best referees."
Of the original pool of 46, nine referees and 12 linesmen remain.
Tamberino, who runs 15-20 miles per week and works weight training into his day job as a driver for a beer distributor, aspires to work the 1996 Olympics and the 1998 World Cup. FIFA probably will still be tinkering with the rules then.
FIFA considered several ways to open up the game after a dreadfully dull 1990 World Cup in Italy in which goals scored dropped to a record-low 2.21 per game. The offside rule was liberalized -- in official's parlance, "even is on" now; the ball was juiced; goalkeepers can no longer use their hands on back passes from defenders; and a prohibition on tackling from behind was to be more strictly enforced.
"They [FIFA] have put more pressure on us to cut the violence out of the game, which in turn will restore some of its beauty," Tamberino said. "I like the changes. Most of them simply give us more power to enforce the rules. We used to be wary of making certain calls, but we now understand that that power is going to be taken away if we don't use it.
"The players have reacted positively. I saw one World Cup game that in any other year, a defender would have taken out the attacker on a certain play, but he thought twice this time. With all of the changes that have been made, I actually thought there would be more goals than this."
Through the second round, the goals per game is up to 2.66, an improvement on three of the past five World Cups and comparable to the other two.