STEVE CARELL screamed in pain after grappling with muscular co-star CHANNING TATUM in a wrestling scene for their new flick “Foxcatcher,” a gripping recap of the bizarre 1996 murder of Olympic wrestler DAVID SCHULTZ by his flipped-out former pal, millionaire JOHN DU PONT.

Channing, making a wrestling move, expertly flipped Carell – who was supposed to land expertly on his feet, but instead – Ker-POW! – he landed on his HEAD!

As everyone rushed to help, Carell kept saying he was okay and tried to laugh off his painful head-banger, but two hours later, Funnyguy could barely move his neck and an on-set medic finally fitted him with a brace.

The aching star bounced back and felt fine just a couple of days later, but after wrestling with how close he’d come to serious injury, wisely decided to let the stuntmen wrestle with all future stunts.