If CHANNING TATUM ever thought MILA KUNIS was NOT a knockout, he absolutely does now!

Pandemonium broke out and production abruptly halted during filming of their new flick “Jupiter Ascending” when the hunk accidently punched his cute co-star during a fight scene…and knocked her out cold!

“Mila was supposed to run to Channing’s left side while he threw a punch from his right side,” said My SpyWitness.

“But she got her directions crossed, ran the wrong way – and Channing’s fist slammed her cheekbone!”

Knocked off her feet, the tiny star hit the ground hard. Horrified, Channing dropped to her side, screaming for someone to bring ice and get a medic.

Said the source: “He kept yelling her name over and over, until Mila finally looked up and said, ‘Will you please shut up and stop screaming at me!’ She’d been knocked out for several seconds, but when medics arrived she insisted she was fine and refused medical attention. She felt a bit woozy after she was helped to her feet, and the director wanted to cancel the shoot – but Mila refused, saying she was afraid her jaw might be too swollen the next day. Makeup people kept applying ice between takes, and Mila was right – next day she was sporting a bruise that had to be covered with heavy foundation.” A cheer for feisty Mila, folks…YAAYYYY