Twin, lose or draw: Sabrina Flores plays for the U.S.; Monica for Mexico

Sabrina Flores, left, claps hands with her sister, Monica. The duo play for the United States and Mexico, respectively, in soccer. Ian Walton/FIFA/Getty Images

One wore red, white and blue. The other wore green.

Most siblings are used to heated backyard battles. Usually the rivalries never get beyond the family home.

The Flores twins, Monica and Sabrina, made soccer a shared passion. They practiced hard against each other while growing up, scarcely imagining that one day at the under-20 World Cup, they would be on opposite sides, with Monica representing Mexico, Sabrina the United States.

The identical twins started their soccer journey together.

"We were involved in region and [Olympic Development Program]," said Monica. The twins attended youth national team camps together from the age of 13. A couple of years later, things changed.

"At U-16 level, things started to go differently for me and my sister," Monica said.

She continued to play at a high level, joining Sabrina, the elder by 11 minutes, at Notre Dame where both study pre-med. But she was no longer brought in to U.S. youth national team camps. Monica then decided to try another route.

Notre Dame hosts Mexico's under-20 team annually for a preseason match. Two years ago, knowing Monica was eligible through her father to play for Mexico, Notre Dame head coach Theresa Romagnolo intervened.

"During warm-ups, I was talking to their head coach at the time, Leo [Cuellar]," Romagnolo said. She told Cuellar about Monica's eligibility. "Anytime I can recommend a player for a national team, I'm going to do it. It's an opportunity. To play at that international level can be really special."

Mexico's coaches liked what they saw from the hard-running, possession-oriented defender.

"From then on, I got called into Mexico camps," Monica said.

"It just happened that different opportunities were presented to us." Sabrina Flores, Notre Dame midfielder/defender

She adjusted quickly, practicing Spanish with her teammates. Mexican-Americans make up a sizable portion of Mexico's women's teams at all the different youth and senior levels. "We're all united to represent Mexico," Monica said. "It's one of the greatest feelings."

"Once we started our respective different national team programs, me with the U.S., Monica with Mexico, we knew at some point that encounter would happen," Sabrina said.

The added scrutiny on their unique situation made them both a bit uncomfortable.

"There was attention beforehand -- the twins battle, a household divided," Monica said of the lead up to November's under-20 Women's World Cup quarterfinal clash in Papua, New Guinea.

"Everyone would turn their heads to us just because we are from the same family, but playing for two different countries," said Sabrina. "It just happened that different opportunities were presented to us."

"I was so proud to see them on the field together, representing different countries," said Romagnolo.

Monica and her Mexico teammates held a one-goal lead late into the second half. Sabrina was subbed out in the 73rd minute as the United States team desperately sought an equalizer. It came eight minutes later. In the final moments of injury time, the Americans scored again, eliminating Mexico from the tournament with the 2-1 result.

"The U.S. came out winning the game," Sabrina said. "I was so happy for my team and how hard we worked, but I also had the feeling within myself that my sister was really sad and disappointed."

Monica was unable to hold back tears. Sabrina went immediately to console her.

"I couldn't control what I was feeling,” Monica said, adding she was grateful for her sister's understanding. "It shows that no matter what, we'd always be together. The game wouldn't divide us. Our innate reaction was to comfort each other and to feel sympathy for each other."

What neither was aware of then was their moment together was broadcast and shared on social media all over the world. Messages began pouring in for the twins about how their sisterly affection at a competitive event touched many.

"The uplifting messages to keep going, and to have support from a huge variety of people, it meant the world to me and my Mexico team," Monica said.

Though she didn't take her sister's gesture of comfort for granted, Monica wasn't surprised by the combination of tough competitor and tender consoler in Sabrina.

"That's what makes us the players that we are, always constantly having each other's backs, pushing each other when we need to or just being by each other's side to give each other help," said Monica.

"They have similar values, aspirations," Romagnolo noted. "There's a lot of respect. When you're going up against an opponent of that caliber every day, you're going to continue to grow."

Going forward, the university juniors want to close out their college careers together and continue to pursue their soccer dreams. Monica has already appeared for Mexico's senior team. Sabrina is hoping to make the USWNT. Both understand as regional rivals, they may face off against each other for years to come internationally and accept that as the price of success on the highest level. One dream scenario would echo their Notre Dame experience by making the roster of the same pro club.

"If we could be playing together, we'd definitely be doing that," Sabrina said.