Ouch! Jimmy Fallon gave Jake Gyllenhaal one violent greeting on The Tonight Show on Tuesday, July 21.

The Nightcrawler star, 34, stopped by the show to discuss his new boxing movie Southpaw and fittingly found himself on the receiving end of a slap from the talk show host. Gyllenhaal agreed to play a game of Slapjack with Fallon, 40, taking a seat across from the comedian at a card table.

"Jake and I are about to play a game that we invented here on the Tonight Show called Slapjack," Fallon explained. "It works the same as blackjack but at the end of each round, the winner gets to slap the loser across the face with a giant prosthetic hand."

With his other hand impaired with his finger cast, Fallon then showed off his massive, fake hand on his opposite arm. He then prompted Gyllenhaal to deal the two of them in, flipping cards as they tried to score 21.

Fallon took the first hit, grimacing as Gyllenhaal showed off his own huge hand. He wasn't safe for long, however, as Fallon soon returned the favor.

Find out who wins the game and see the two stars' painful slaps in the video above!

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