Irene, South Africa ? The flailing, groping and grabbing have been scrutinized countless times since a referee’s call made all the difference in Friday’s World Cup tie between the United States and Slovenia.

For U.S. fans, coaches and players alike, slow-motion replay of the mayhem has been the only means of reading the mind of referee Koman Coulibaly, whose call in the 85th minute negated Maurice Edu’s potential game-winner.

After doing some film study of his own, midfielder Clint Dempsey had this to say Sunday when asked if it was his roughhousing that prompted the foul: “If you freeze-frame that play, three of our guys are in a headlock. To single me out — that that’s the play that I caused trouble on — I don’t think you’re really watching the game.”

It’s not that Dempsey was professing innocence from the first minute of Friday’s match to the last. In a hardscrabble career that got its unlikely start in Nacogdoches, Texas, the 6-foot-1, 170-pound midfielder has more than held his own against the game’s toughest defenders.

Nor was he trying to shift blame to a teammate. By all accounts, the U.S. squad that’s battling for a place among the World Cup’s final 16 is solidly in the fight.

Dempsey’s larger point was that the rules of engagement change in the waning minutes of a World Cup match. And despite FIFA officials’ pre-tournament warnings that no contact would be allowing during all-important corner kicks, that hasn’t proven the case.

It likely never will be known which transgression among many caught Coulibaly’s eye. But as the World Cup marches on, it appears that each referee tolerates a different amount of physicality in front of the goal. And it’s up to players to figure out if that standard is a strait-laced gentleman’s game or soccer’s version of mixed martial arts — and to push that limit to its fullest.

“You have to gauge that,” Dempsey said. “The ref in this game (Slovenia) was letting things go in the box, so you’ve got to be physical. If someone has their arms around you, I’m not gonna sit there and be like: ‘Okay, this is fun,’ I’m going to try to bust out of it and get in position to score a goal.”

If the limit of what’s permissible is murky in this World Cup, as Dempsey suggests, it’s sure to be tested anew when the United States faces Algeria on Friday knowing that only a victory will guarantee passage to the next round. Algeria, scoreless through two matches, will be equally desperate for a victory to avoid the shame of a last-place finish in Group C.

The Americans have demonstrated a disturbing knack for falling behind early, conceding a goal to England after four minutes of play and allowing Slovenia a first score at the 13-minute mark.

But they rallied on both occasions, pushing the pace to an exhausting extent after falling behind, 2-0, against Slovenia.

“We’re in a World Cup,” Dempsey said. “We’re going to be so motivated, that’s not going to affect us. We know what we’ve got to do to get our minds and bodies right for this game. We’re going to give everything we have. We’re going to leave our lungs and our heart on the field.”

U.S. goalkeeper Tim Howard says he’s confident his team will manage the fine line between necessary aggression and the foolishness that often results in penalties.

“If tackles start flying in, and we need to stand up for ourselves — you best believe we will,” Howard said. “I don’t expect anything terrible to go on. But you know what it’s like at this level, particularly with the last 90 minutes. Everything is on the line. Emotions run high.”

Although sequestered on a dairy farm north of Johannesburg, U.S. players have gotten word of the outrage among their supporters back home over the call that nullified Edu’s goal. And it has been gratifying, Howard said, knowing so many Americans are invested in their results.

“For our American fans to be so up in arms about it does show that, number one, they care,” Howard said, “and number two, they are getting hip to the game and starting to understand how it all works.”