Kathryn Nesbitt became the first woman to referee a championship match in professional men's sports in North America in December, when she took the field for the MLS Cup between Columbus Crew and Seattle Sounders.

But for anyone who had been paying attention, Nesbitt's inclusion was anything but a surprise. The recognition was preceded by her assignment to the MLS is Back Tournament final earlier that year, where she became the first woman named to a league final officiating crew. The voting results, made public by MLS, also vindicate her winning of the award.

But why become a referee in the first place?

"Everyone has their own path," Nesbitt told FIFA.com. "I started as a kid as a summer job, and that kept me involved in soccer and eventually kept me involved in sports. I really liked staying active. It can be competitive in its own sense as well, so to have those opportunities to strive to be the best at something in kind of an athletic form was great for me, so that’s really what pushed me to keep moving forward with it."

Nesbitt's passion outside of football is in analytical chemistry and teaching. They may sound as far away and unrelated to football as one can get, but the reality is the two are intertwined.

“I was a professor of chemistry up until two weeks before the Women’s World Cup in 2019. I spent ten years doing my own research and starting my own lab at the university (Towson University in Baltimore). My background in research is on figuring out better ways to analyse brain chemicals, and our lab focused on developing, improving and optimising the techniques for sampling brain chemicals and then analysing them."

Her analytical personality has been with her from the beginning, but how has that trait helped her progress as an assistant referee?

“Specifically for me, you’re constantly making decisions and they’re not always black and white," Nesbitt said. "It’s about being able to take in a lot of data at one time – how a tackle actually happens, the player’s reaction, what’s going on in the game – and make the best decisions.

"Referees are also incredibly dedicated to their role as well. We take games just as seriously as the players. Our preparation is actually quite similar to what they’re doing.

“There are black and white decisions. One defender pulling down the attacker who’s five feet from goal is always going to be denying a goalscoring opportunity, but that’s never actually how those things play out. And one soccer scenario isn’t going to happen exactly the same way again. The game’s always changing. My main role as an assistant referee is the offside rule, and that isn’t always as black and white as it looks sometimes."

Nesbitt's professional debut was in 2013, in the inaugural match of the National Women's Soccer League (NWSL) in front of a large crowd. Contrary to what one would assume, she says the larger the crowd, the more focused she becomes. Due to the global pandemic, Nesbitt has had to adjust to the job in near silence for the past year. She spent seven weeks living inside "the bubble" as part of the officiating staff for the MLS is Back Tournament, which ran from 8 July to 11 August 2020.

"The first couple of days everyone was a little shaky on how it would all work, but we were able to ease in and feel fairly comfortable and safe within a few days," she said. "I really give a lot of credit to MLS for helping us with that. We were very much in a bubble. We could not leave at all.

"What that atmosphere does, at least for referees, is you are so honed in and focused on soccer and what your job is that when it comes to doing those games, you are more prepared than normal. You’re basically living, eating, breathing soccer all day long."

But referees are human beings, so how mentally draining can tournaments like that be?

"The part about being away from your family is for sure draining," she said. "That’s probably the hardest piece. The hotel we were in had some great facilities for us. We had a great group of motivated officials.

"Even on those hard days, where you referee the 9am game in the Orlando heat and you’re exhausted the rest of the day, you still could sit down and have dinner with your friends and get through those hard times. Thank God for video chatting now. We all sent flowers home to our significant others to keep them happy.”

Nesbitt is acutely aware of the perception of referees from fans and players and coaches.

"We understand we will be the bad guy," she said. "When there are mistakes, it's always a human feature of us. Referees try to be the best for the game and we want to be the best in what we do. We are just upset as anyone when a mistake is made."

How has refereeing changed her and how can she see that she's a different person today than she was yesterday?

"The biggest thing it has taught me is how to take away positives out of a situation and apply that in a lot of areas. I perform my best when I’m happier and more positive and taking advantage of incredible opportunities and not taking anything for granted. That's a huge aspect that I'm able to apply in life with family and at home."

Nesbitt is a fan of the game just like the rest of us. She's professionally trained in video assistant refereeing and she insisted that "no-one wants to slow the game down."

Being an assistant referee involves a lot more than getting offside calls correct. They have to catch any touchline ball going out or not, assist the head referee on any fouls or off-the-ball incidents closer to them, assist in penalty decisions and the list goes on. They also have to deal with confrontation on a regular basis.

"Everyone develops their own style in dealing with moments, some are strict and stern and some are calm. It's a skill set. I’m pretty direct with players and proactive, and I try to prevent things from exploding."

Just as youngsters look up to their favourite players, there's no doubt that Nesbitt has inspired aspiring female referees across the globe to be their best and reach the top.

"It has been an absolute honour to have people say that I’ve become a role model for women," she concluded.