Shannon Briggs has talked up Logan Paul's punching power ahead of the YouTuber's fight against undefeated legend Floyd Mayweather.
Paul will take on the 44-year-old in the early hours of Monday morning at the Hard Rock Stadium, Miami.
It's widely viewed as an exhibition bout, although Paul has promised to 'take the fight' to Mayweather.
Former world champion Briggs has worked with the entertainer before and claims he can 'hit'.
"Logan, he's a good guy. He's going to shock the world," Briggs said on the Toe 2 Toe podcast (via Sky Sports).
"You know what, keep your eyes on this guy.
"From having trained him and said this, 'you're going to fight Floyd Mayweather one day.'
"I kid you not, I said it. It's happening, and I felt his power before. He can hit.
"Be careful. This might not be what you all think it is. The boy can hit."
Mayweather retired in 2015 as one of the sport's greatest ever fighters. He won world titles at welterweight, lightweight and super featherweight during an illustrious career.
Since then, he's been involved in major crossover fights and PPV events. He took on UFC star Conor McGregor in 2017 and won via TKO. That took his record to a stunning 50-0 (27 KOs).
Mayweather earned a reported $275million for that fight and is expected to gain another substantial paycheck against Paul.
The event kicks off on Monday morning at 1am BST, with the two fighters scheduled to make their ring walks at around 5am.