SAN ANTONIO – Isaac Cruz might’ve stolen the show before it really even began Saturday night.

The Mexican lightweight contender overwhelmed Diego Magdaleno, dropped him twice in less than a minute and viciously knocked him out in the first round on the Gervonta Davis-Leo Santa Cruz undercard at Alamodome. Cruz crushed Magdaleno with two devastating right uppercuts that knocked the veteran lightweight awkwardly onto the bottom rope and abruptly ended their scheduled 12-round IBF elimination match.

Referee Mark Calo-oy quickly stopped their fight just 53 seconds into it, as soon as Magdaleno went down a second time.

The 22-year-old Cruz improved to 20-1-1 and recorded his 15th knockdown. Magdaleno (32-4, 13 KOs), a 34-year-old southpaw from Las Vegas, lost by knockout for the third time in his career.

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