SANDY, Utah — Real Salt Lake head coach Jason Kreis says he knows the exact day when his team and Sporting Kansas City became rivals: March 8, 2011.

And “as odd as this may sound,” it came during a preseason match in Arizona that “got way out of control,” Kreis told reporters this week.

The “very, very physical affair” came as “Kansas City was just starting to implement a really competitive nature about themselves,” he said. “And we were embarrassing them a little bit preseason, 2-0, knocking the ball around.”

Sporting Kansas City's play got rougher as the game went along, according to Kreis. And after they'd tied the game at 2-2, a brawl broke out.

According to game reports, it was sparked by a studs-up challenge by former SKC midfielder Roger Espinoza on RSL midfielder Javier Morales.

“Things got completely out of hand,” Kreis said. “The referee couldn't control it.”

According to match reports, the referee red-carded the wrong Kansas City player. And there were disputed reports that, in the ensuing melee, Morales was kicked in the head as both benches cleared.

“We had to stop the match and walk away,” Kreis said. “And I feel like ever since then, there's certainly been a rivalry. Physical confrontations between players. And you can tell that it means a little bit extra when these two teams play against each other.”

That was certainly true when the two teams, who will meet for the MLS Cup on Dec. 7 in Kansas City — met at Rio Tinto Stadium back on July 20. That match that featured 26 fouls, seven yellow cards and one ejection.

“They bring out the best in us in terms of our competitive nature,” Salt Lake defender Nat Borchers told reporters. “Just their physical matchups and just how they want to play.”