That's Logan Paul telling TMZ Sports a potential boxing match with Antonio Brown is VERY realistic ... claiming he's already in talks with AB's camp.

"I think we might be closer than anyone expects," Paul says.

As we previously reported, Logan called out Brown in December -- saying the NFL star would be the perfect opponent to further his pro-boxing career.

Brown responded on social media -- telling Paul, "Square up." Brown has since told Complex he's down to scrap and wants to train with Floyd Mayweather.

So, when we saw Logan in L.A. promoting his brother Jake Paul's upcoming Jan. 30 boxing match against AnEsonGib on DAZN, we had to ask if all the AB fight promotion was real ... or just a gag.

Logan says he's not messing around -- he's deadly serious about getting a deal done and thinks Brown is highly motivated, too.

Paul says transitioning into fighting helped rehab his image after the incident in the Suicide Forest in Tokyo a few years ago ... and a high-profile match could do the same thing for AB.

"In many ways the KSI fight gave me a purpose. I think this would do this for Antonio Brown -- give him a nice pay day, give him a chance to redeem himself."

Paul thinks the fight could be HUGE -- a la Mayweather vs. McGregor.

"Whether you like him or you hate him, you're gonna pay to see him beat me up, whether you like me or hate me. Or, you're going to see him get beat up and it goes the same for me."

"In so many ways, this fight is so right."

As for the matchup, Logan says he truly believes he can win -- "I'm a pro boxer at this point. I've been doing this for two years now. I think I would give him that work for sure."

As for Jake Paul's next fight ... he ain't messin' around either. The bout will go down in Miami during Super Bowl week. Jake tells us the plan is to beat up Gib and then hit the strip clubs TOGETHER!