The directors, Billie Jean King and two body doubles made the tennis action scenes come to life. (Courtesy of Fox Searchlight Pictures)

The biggest strife with tennis films has been the on-court scenes. The majority of famous actors aren’t very capable tennis players, and the action shots end up looking fake, awkward and utterly disappointing. This is not the case with the Battle of the Sexes, which stars Emma Stone and Steve Carell as Billie Jean King and Bobby Riggs.

Carell brought in some tennis experience, but a skilled body double, Vince Spadea, replicated Riggs’ forehands and backhands. Stone had never seriously played tennis in her life.

“It was incredible to have the doubles that we had in this film. Kaitlyn Christian and Vince Spadea were amazing,” Stone said. “That was really comforting to know I could focus on the details, how she bounced her ball or the beginning of her serve or her backhand and could really try to perfect moments rather than become the No. 1 role player.”

The co-directors, guided by King and Riggs' former coach Lornie Kuhl, brought in Spadea and former USC standout Kaitlyn Christian.

“We auditioned a bunch of people. We needed great tennis players and then we needed people who looked like Emma. She was really good. She had to act as well,” co-director Jonathan Dayton said.

"It all happened really quickly," Christian told Baseline. "I signed a five-week contract for the filming part of it but it took, in totality, around four months. The first month was sitting and getting my hair cut and my hair died. Next was practicing with Emma on the court and then filming."

Christian was, and still is, pursuing a professional playing career so she had to take four months off from traveling the ITF Pro Circuit.

"I was still able to practice on days that I wasn't filming," Christian said. "But some of the hours filming were 12-14 hours—it was nothing that I expected. You see on the screen one scene takes 5 seconds, but it could take us 10 hours to film."

Still, the 25-year-old landed one-on-one time with one of the legends of the sport, King. 

"It was so cool spending some time on the court with her because for the first part of it she showed me a little bit of how she played, but the second part was just my normal tennis game," Christian said. "She was so concerned with trying to help me in real life."

For Christian and Spadea, a former Top 20 player, it was a lot more than just playing some points out. The game style in the 1970s was very different to what is today.

“The original match, there's some amazing points in that. We studied that. We edited it down to a 10-minute edit. We want this kind of a player. We're not going to choreograph it, but they practiced a lot of the kinds of plays that were in the match,” co-director Valerie Faris said. “Kaitlyn had to learn the wood racquet, Billie's grip, the backhand style.”

It took a lot of work, but Christian and Spadea mastered the wooden racquet game style. 

"Vince and I spent hours  and hours together practicing with wood racquets. After a few months I kind of got used to it, but it took a while," Christian said. "The first month we practiced together and then we'd send video to the directors, and they'd give us stuff to work on. Behind the scenes we were playing with it quite a bit."

The end result is as realistic as if you’re watching real footage of the 1973 match. The Battle of the Sexes is out in select theaters, and premieres worldwide on Friday.