(ABC News) -- Caroline Pla has played football for six years – more than half her life. The 11-year-old offensive guard started playing Pop Warner flag football when she was 5, and when she hit fifth grade, she joined the Junior Varsity Catholic Youth Organization team, the Romans, in the Archdiocese of Philadelphia.
According to her coaches and teammates, Caroline was a good player, chosen to play on the all-star team at the end of the 2012 season.
But the season has ended, and an archdiocese rule -- which bans girls from playing football in the Catholic Youth Organization -- could bring Caroline's promising football career to an end.
"After the second game of the season, we got a call from the archdiocese telling us there had been a complaint, and that Caroline had to stop playing immediately," Marycecilia Pla, Caroline's mother, told ABC News. "They eventually agreed to let her finish the season, but that was it."
Pla said her daughter had played Catholic Youth Organization football for two years, and nobody on the team, including the coaches and parents, knew that girls weren't allowed to play in CYO games. The phone call came as a total surprise.
"At first, everybody was like 'Whoa, there's a girl,' but then they accepted me," Caroline told ABC station WPVI in Philadelphia.
Her parents and coaches delayed telling Caroline that 2012 could be her last season, waiting until the Romans lost its second play-off game at the end of the season.
"She wasn't happy about it, but her first question was 'What about Gracie?" Pla said. Gracie is Caroline's biggest fan, a fourth- grader who went to all the Romans' practices and games, and couldn't wait to follow in Caroline's cleats when she got to fifth grade.
Caroline also worried about the other girls who'd looked up to her and wanted to play CYO football when they came of age.
"After the all-star game, a little third-grader came up to Caroline and asked to have her picture taken with her," Pla said. "Caroline wants to make sure she can play."
At the end of the season, Caroline called the Archdiocese of Philadelphia to thank it for letting her to finish the season, and to ask it to change the rule so that she could continue to play football, but she never heard back, her mother said.
So Pla – with the urging of her 16-year-old son – started an online petition at Change.org -- the online cause-fighting petition site where a teenage girl petitioned Hasbro for gender-neutral Easy Bake Ovens and another implored EA Sports to include female characters in its soccer video games -- to collect enough signatures to get the Catholic Youth Organization to change its rule.
"It's been incredible to see all these people support her," Pla told ABC News. "Her teammates, Sam Gordon, the 9-year-old girl football player who's been in the news, the players from a women's professional football league, even a nun from the archdiocese all signed it and told her to keep fighting."
The petition, "Archdiocese of Philadelphia CYO Office: Stop Discrimination – Change the CYO Football Rule – Allow Girls to Play," has nearly 8,000 signatures from people around the world. The most popular comment on the petition is from one of Caroline's former teammates.
"I played with Caroline this year, and she is AMAZING! Let her keep doing what she loves," Michael Cuozzo wrote.
The Philadelphia Archdiocese has defended its rule, calling it a necessary safety measure.
"CYO football is a full-contact sport designated for boys," archdiocese spokesman Ken Gavin wrote in a statement to ABC News. "There has been some perceived ambiguity in the policy regarding this point. It is currently being reviewed and will be addressed moving forward to provide complete clarity."
Pla said this explanation for the rule isn't fair to her daughter, or her daughter's coaches.
"At this age, Caroline is bigger than some of the boys, and she's gone up against boys both bigger and smaller," Pla said. "But she had great coaches, so she's playing the right way, the safe way.
The boys never treated her different because she's a girl, and she was a good player."
The archdiocese has said it's reviewing its ban, and Pla that now that now that the holidays are over, she hopes to see a change.
"Her teammates don't want to see her go out this way," Pla told ABC News. "They want to see her back next season. And Caroline wants to play but mostly just wants to make sure other girls can play too."