The beef started during the game ... 26-year-old Simmons tackled Ravens WR Zay Flowers low, and 30-year-old Odell objected, seemingly kneeing Jeffery. That didn't go over well with the DE, who shoved OBJ to the ground, drawing a 15-yard penalty.

After the game, which the Ravens won 24-16, Simmons clearly wasn't over what happened with Odell.

On his show, the Punch Line Podcast with Marlon Humphrey, the 3x Pro Bowler says he was hanging out on the field at Tottenham stadium when he saw the huge, 6'4", 305 lb. defender waiting, helmet on.

A bit strange, but Marlon says he assumed Simmons was waiting for a family member.

Alas, that wasn't the case ... moments later Humphrey heard someone yelling for Ravens' security.

"I turn around, [Beckham Jr. and Simmons] are genuinely like fighting. I am pretty sure Odell is grabbing his facemask," Marlon described.

"They had to be separated and everything. I don't know how this has not [been reported]. I mean, [Simmons] is crazy. He wanted that fade from Odell."

Order was eventually restored ... and the two stars went their separate ways. Probably best for Odell ... who is just 5'11", and weighs under 200 lbs.

Of course, it's not the first time Odell's mixed it up on the football field. Recall the infamous Giants vs. Panthers game back in 2015.