By TMZ Sports
Former IBO welterweight champion Chris van Heerden knows firsthand what it's like to BOX Conor McGregor -- and tells TMZ Sports the guy is gonna get ROCKED by Floyd Mayweather on August 26th at the T-Mobile Arena in Las Vegas.
The 29-year-old professional fighter stepped in the ring with Conor in May 2016 to spar for a few rounds -- and dominated the UFC star.
And to rub salt in the wound, van Heerden says he was out of shape and had just gotten back from vacation when around the time of the sesh ... and still "landed at will" on McGregor.
We asked straight-up if Conor has the knockout power to beat Floyd, van Heerden's response -- "No."
But just because he doesn't believe on Conor doesn't mean he won't get into business with him -- Chris says he wants to fight on the Mayweather v. McGregor undercard ... and he even names his opponent, Lamont Peterson.
"I sparred with Conor, coming from a holiday, out of shape, and I was just having fun and being me. I wasn't even focused, in camp, out of shape. I keep reading these comments that Mayweather is going to have his hands full with landing on Conor McGregor, because of Conor's speed and movement. I'm no Mayweather and I was out of shape and landing on Conor. We landed at will. Its crazy to compare a boxer who is 0-0 to a legend, who when you compare his resume has beaten the best in the world," Van Heerden said.
"No [he can't knock Mayweather out], not with 10 ounce gloves. [Mayweather has] been rocked before. He's been hit by Maidana, he's been hit by Sugar Shane Mosley. He's been hit buy guys who can punch and he didn't go down."
