Cuban Olympic hero Erislandy Alvarez was stopped in the second round by Jose Nunez in a stunning upset Friday at Gimnasio Club Mexico in Santiago, Chile.

Alvarez, 6-1 (2 KOs), who won a gold medal at lightweight in the 2024 Paris Games, had previously been unbeaten since turning pro in February 2023.

With just over a minute gone in Round 2 on Friday, Alvarez seemed to throw caution to the wind, leading with power, charging forward and squaring up to unleash both hands with Nunez hemmed into a corner.

But Panama’s Nunez, 18-0-2 (8 KOs), punched his way out, and after missing with a looping right hand, he appeared to land the right around Alvarez’s guard on a second attempt. Alvarez crumpled backwards to the canvas, and when he swayed and staggered after popping back to his feet, referee Luis Pabon needed only a moment to decide to wave off the fight.

The time of stoppage appeared to come at 1:33 of the second round.

The decisive one-punch knockout loss to a little-known lightweight marks a major setback for Alvarez, a 25-year-old junior welterweight prospect from Cienfuegos, Cuba.

Nunez had compiled an impressive enough record entering Friday night, but this win in particular should dictate that he be evaluated differently. Previously, he had fought mostly low-profile competition. But the Alvarez stoppage, combined with a unanimous decision win over Omar Salcido Gamez in 2023, signal that the 27-year-old southpaw Nunez may be a late bloomer ready to crash the rankings at 135lbs.