For months, there had been speculation about who'd join Flair inside the ring for arguably the biggest night of his career ... so it's fitting he chose his daughter Charlotte's husband, Andrade.

As for their opponents, Flair and Jarrett have history going back to their WCW, WWE, and eventually the TNA days. Ric and Lethal have a close relationship inside and outside the squared circle, as Jay has been training with the "Nature Boy" ahead of the big match.

Lethal has been one of the men responsible for helping Flair regain his in-ring confidence ... exchanging bumps with the 73-year-old Hall of Famer, who hasn't lost much of the mojo that made him one of the greatest entertainers in wrestling history.

As Flair prepares to take one final strut down the aisle as a performer, he recently told Mojo and Babcock on the "TMZ Sports" TV show he was medically cleared by his doctor, so he isn't all that concerned about his health failing during the match.

Flair -- who has a pacemaker and takes blood thinners after nearly dying several years back -- says he won't take his medication the day of the big match.

As for what to expect in the squared circle, Naitch told us while he'll never be the exact same competitor he was in his heyday, he's still got more than enough to go out there and put on a great performance.

"I'll never run at 100% again. But, I'll be running at 80, 85%," Ric told us in late May.

The spectacle of Flair -- a 16-time World Heavyweight Champion -- wrestling at this stage in his life has garnered the admiration and respect of his contemporaries like Booker T, who lauded the "dirtiest player in the game" for having the desire to perform in his 70s.

"What Ric Flair is doing, he's doing that because he loves this business, man," Booker T recently told us.

"Ric Flair told me a long time ago that he would never retire. That's that guy, man."