Actor Hafthór Júlíus Björnsson — better known as Gregor Clegane, the Mountain, from HBO’s Game of Thrones — joined the Phillies for batting practice on May 15.

After getting a look at who was in uniform for the Phillies, their opponents the Arizona Diamondbacks insisted on picking a champion of their own.

@Phillies We choose one of our reptilian ancestors to be our champion. ???? pic.twitter.com/CWM6Zy64u0

— Arizona Diamondbacks (@Dbacks) May 15, 2015

[Thanks to Martin Morse Wooster for the story. (Photos and video by Alex Nolen, MLB.com / Real-Time Correspondent.)]