Them's fighting words, Jimmy!
Well, first, Tatum reacted the way one would expect: He basically almost laughed in Fallon's face.
"I'm serious—I'm been working out a lot lately," Fallon deadpanned. "Curves gym."
The 39-year-old host is not kidding about his on-air physique—with the help of a green screen, the Tonight Show host flaunted a well-sculpted figure during a shirtless "Nip Sync" battle with Terry Crews. He has also arm-wrestled other celebrities on the program before. In September 2013, he faced off against Hugh Jackman.
"I'm pretty sure I can beat you," Fallon told Tatum.
"That's a really interesting theory and all, but we'll see," the actor replied.
Still wearing their suits, and with the actor's muscles bulging in his tight sleeves, the two began the undeniably epic face-off and rattled off lines about what they planned to do if they won. One of Tatum's threats was particularly menacing.
"After I wiiiin, I'm gonna start texting you, so you see that little typing bubble pop up," Tatum said. "Then I'm gonna wait like five years. And then just text, 'K'!"
Watch the video above to find out who won!
(E! and NBC are both part of the NBCUniversal family.)