8:59 AM PT -- TMZ Sports talked to Evander Holyfield ... and it's clear, Iron Mike ain't the only one who feels like they still got it in the squared circle.
"My 1st week back in the gym and I feel great. I'm looking forward to stepping up my training sessions and intensity as I prepare for my fight."
HOLYFIELD-TYSON III IS REALLY GONNA HAPPEN ISN'T IT?!?!?!
Here's further proof Evander's gearing up to fight Iron Mike for the 3rd time ... posting video that sure feels like a clap back at Tyson to us!!!
Just hours after Mike released more training footage of him terrorizing mitts and claiming he's "back" ... Evander posted similar clips, capping them off with an "I'm back" of his own.
That definitely means a rematch is on the way, right?!?!?!
Of course, the two former champs have already publicly stated they're looking for charity fights in the upcoming months ... with Holyfield even telling TMZ Sports the other day he's down to make another rematch with Tyson happen.
If it does eventually get scheduled ... we're not sure we've ever been more fired up to see two 50-somethings square off -- 'cause did you see Mike's clips Monday?!
But, Evander DID win their first two matchups ... and he ain't looking bad against the mitts himself!!
Soooo ... just tell us when and where the fight's happening now, please!!!