Floyd Mayweather Jr. dominates Japanese kickboxer with three-knockdown exhibition

Was it worth forking over $9 million? Hardly.

But the scene of Floyd Mayweather Jr. standing over the Japanese kickboxer he’d just knocked down, as the spaghetti-legged fighter failed to find his footing while falling nearly halfway backward across the ring, was rich indeed.

Mayweather dominated the younger, far lighter super-bantamweight-sized Tenshin Nasukawa, knocking him down three times in the first round before the kickboxer’s cornerman father threw in the towel.

The exhibition outside Tokyo in Saitama, Japan, was promoted on the Rizin Fighting Federation’s New Year’s Eve showcase.

Mayweather successfully negotiated not only the massive appearance fee, but the stipulation that there be no kicking allowed from Nasukawa, even though the weight disparity likely would’ve never allowed the bout to happen in the U.S.

The outcome showed why.

Mayweather scored the three knockdowns, and could’ve been excused for failing to suppress a smile following the one from a left hook that left Nasukawa unable to find his feet. A sudden right hand dropped Nasukawa again in a corner, and Mayweather thrust his waist toward the downed fighter before the towel was thrown.

Mayweather executed a little dance at the end.

“It’s all about having fun,” Mayweather said after repeatedly referring to the exhibition as “entertainment” throughout the buildup to the bout.

But Nasukawa was weeping afterward, and Mayweather sought to preserve the youngster’s dignity by saying he was “still a great champion … Tenshin is still undefeated. I’m still undefeated.”

The 41-year-old Mayweather (50-0) is believed to be heading toward a boxing rematch with Manny Pacquiao should the favored World Boxing Assn. secondary welterweight champion defeat former four-division champion Adrien Broner Jan. 19 at the MGM Grand in Las Vegas.

Mayweather last fought a legitimate pro boxer in 2015. He returned for another massive pay day in 2017, stopping then-UFC champion Conor McGregor by 10th-round technical knockout in Las Vegas.

“He is first class,” Nasukawa said.

lance.pugmire@latimes.com

Twitter: @latimespugmire