Sarah Thomas as NFL referee could be happening soon and could be a barrier broken down in the U.S. most popular professional sport as its first ever female official.

The 39-year-old could become an official NFL referee for the 2014 season. Sarah Thomas is one of the 21 officials who are in the NFL's higher-level training pool, according to the Huffington Post. When a position opens up, one of the 21 will get the opportunity to become that next official. It doesn't neccasarily mean it would be Thomas, but it could happen.

"I didn't set out to break a glass ceiling or a gender barrier," Sarah Thomas told Bloomberg in early July about becoming the first female NFL referee. "If you're doing things because you love them, then things have a tendency to just kind of fall into place."

Violet Palmer is the one and only female NBA referee as she and another woman were signed to the NBA in 1997, when Palmer officiated a game for the season's opener and was the one of the two females to last in the NBA. Palmer faced sexism when she was offered an opportunity to officiate the NCAA Division I men's tournament in 1996. She accepted, but the offer was later retracted when NCAA members balked at the idea of having a female referee male players.

Sarah Thomas worked as a line judge during the 2009 Little Caesars Bowl and became the first female official to ref a bowl game. In 2011, she became the first woman to officiate in a Big Ten stadium when Northwestern hosted Rice on November 12.

"[Thomas becoming a permanent official would be a] good positive first step that begins to reflect the gender dynamics of the NFL audience," Aine Duggan, president of the National Council for Research on Women, told Bloomberg. "It's important for women to see themselves reflected on and off the field. Having a woman referee is a good step that begins to do that."