ONTARIO, California – Rene Giron upset one of boxing’s top prospects Saturday night.

The unheralded Mexican came to Karlos Balderas’ home area and knocked out the highly touted 2016 American Olympian late in the sixth round on the Tony Harrison-Jermell Charlo undercard at Toyota Arena. Giron knocked down Balderas with a left hook late in the sixth round, three rounds after he first floored the previously unbeaten lightweight in this all-action, back-and-forth fight.

Balderas beat referee Ray Corona’s count, but Corona still stopped their scheduled eight-rounder with one second to go in the sixth round. Giron (14-1, 8 KOs) knocked down Balderas late in the third round, but Balderas barely beat Corona’s count and was saved by the bell.

The 24-year-old Balderas (9-1, 8 KOs), of Santa Maria, California, wasn’t afforded that same opportunity very late in the sixth.

Giron drilled Balderas with two left hooks at about the halfway point of the sixth round. Balderas took those shots well and fired back an overhand right that connected.

A counter left by Giron clipped Balderas when he was in a vulnerable position late in the sixth. Giron was bleeding from his nose when he blasted Balderas with that fight-ending punch, the consequence of a right uppercut by Balderas earlier in the sixth.

Balderas boxed well in the fifth round, when he seemed to have regained his legs following the knockdown two rounds earlier.

Still affected from suffering a knockdown late in the third round, Balderas blasted Giron with a low right hand just after the midway mark of the fourth round. Corona didn’t deduct a point from Balderas, but he did issue a stern warning for that foul.

Giron wanted to continue as soon as possible. Corona made him walk back and forth, across the ring, to show he was fit to fight after absorbing that low blow.

Giron’s left hook landed about 30 seconds into the third round. Toward the end of the third round, after Balderas had some success, Giron nailed him with a short left hook that knocked Balderas flat on his back.

Balderas was slow to get up, but barely beat Corona’s count. Once he reached his feet, Balderas stumbled backward, into a neutral corner. Corona didn’t stop the fight and the bell sounded to end the third round before the action could continue.

Giron landed a flush left hook early in the second round. Giron got the better of an exchange of left hooks late in the second round as well.

A right hand by Balderas knocked Giron off balance in the middle minute of the first round. 

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.