With reporting by Nicole Pajer

Cleveland Cavaliers forward LeBron James isn't just basketball royalty, he's about to take the crown on the big screen as well when "Trainwreck" hits theaters tomorrow (July 17).

James plays LeBron James, best friend to Bill Hader's sports medicine doctor character -- and romantic interest to Amy Schumer's character -- Aaron. While it may seem a stretch to land the four-time NBA MVP for your movie, Schumer, who wrote and stars in the movie, said that he was the only option for the part.

"I just wrote him in the script because he's the only basketball player that I've ever heard of and it's a good thing that he said yes," Schumer told MTV News. "I don't know who would have done it."

Hader, who had met and worked with James when the basketball player hosted "Saturday Night Live," said that he and director Judd Apatow went to see James play, then took him to lunch the next day to pitch him the movie.

"He thought it was really funny, he thought it was great," Hader said. "The last week of shooting was all the LeBron stuff, and we were just kind of convinced this isn't gonna work out. We were shooting the movie for months, just going LeBron is never gonna -- something is going to happen and he can't do it, which would make total sense."

Luckily, it all worked out. In the movie, James is a "Downton Abbey" loving romantic, as well as an essential sidekick in Hader and Schumer's dramatic relationship. While Hader said he and movie BFF James would hang out between takes, life didn't imitate art in every detail.

"He didn't want to watch 'Downton Abbey' with me, weirdly enough," he said. "Tried to get him to do it, and he said, what did he say...he said no."

Schumer revealed that despite James' serious-seeming persona, the 6'8" basketball player "just showed up and he was so funny. I think he's going to surprise people."

"He's hilarious and is not at all too cool for school," Schumer said. "He's totally down to play around and joke about everything in his life. And he likes me more than [co-star] Vanessa [Bayer]."

That's not all she revealed.

"LeBron's my dad."

We haven't quite verified that one yet, but can confirm that James is totally hilarious in "Trainwreck," in theaters July 17.