Originally published on ProWrestlingSheet.

Chris Jericho is finally opening up about his backstage altercation with Brock Lesnar at SummerSlam ... as well as confirming that Randy Orton sustained a concussion at the PPV.

Jericho appeared on You're Welcome with Chael Sonnen and was very open about the real-life incident when the MMA fighter inquired ... saying, "I just thought the finish of that match was very brutal and very violent, and I just didn't know if Randy was ok."

"I said something and he said something, next thing you know we're nose-to-nose kinda yelling at each other and it diffused fairly quickly." Y2J adds, "Brock is a trained fighter and he's a beast, but I'm not the type of person to back down from anybody."

The RAW Superstar noted that the finish of Lesnar's match was none of his business ... however, he explained, "When I see a friend of mine lying in a pool of his own blood, whether it's a work or not, that's real blood. That's a real concussion that he suffered.  So I wanna go check and see if he's ok."

For more details on the altercation, check out OUR REPORT FROM AUGUST. It syncs up pretty closely with the few details Jericho has now revealed.

Chris' full podcast interview can be HEARD HERE.  Listen to the Brock clip below.