Nick Chubb and Saquon Barkley both think they can out-squat each other ... and there's only one way to solve this:

NFL STAR SQUAT SHOWDOWN FOR THE AGES!!!

The Cleveland Browns running back was answering questions during an AMA with Bleacher Report this week ... when he was asked straight-up -- who would win in a squat-off between the 2 stars.

"It'd be me," Chubb said. "Don't let his leg shots fool you."