De Los Santos, the Central American and Caribbean Games champion, had only moved up to flyweight in April but proved far too strong for Cintron, emerging with a unanimous win to book his place in the last eight.

The Puerto Rican, second in the International Boxing Association (AIBA) World Series of Boxing rankings to earn his country a quota place for the Rio 2016 Olympic Games, was unable to live with the power of his opponent as he exited the competition at the first round stage.

Elsewhere on a packed opening day at the event, American youngster Brent Venegas secured a surprise success against Brazilian veteran Juliao Henriques Neto in the flyweight class.

Venegas belied his tender years to clinch a unanimous victory over Neto, the gold medallist at the AMBC American Confederation Boxing Championships four years ago.

Nanjing 2014 Summer Youth Olympic Games silver medallist Juan Ramon Solano of the Dominican Republic also comfortably progressed to the next round as he was rarely troubled in his unanimous victory against Ecuadorian Abel Mina in the welterweight division.

Another shock occurred in the super heavyweight category as Argentina’s Nicolas Espindola, who represented his country at Nanjing 2014, suffered an unexpected defeat at the hands of Rafael Duarte Lima of Brazil.

There was some success for Ecuador as Carlos Andres Mina, one of the hot prospects in the light heavyweight competition, was awarded the win on all three judges’ scorecards in his bout with Brazil’s Michel Borges.

“I knew my Brazilian rival and I prepared for a big battle as he is experienced in the international competitions,” Mina said.

“I have tried to perform my way, and I have got some new combinations which I know surprised my opponent.

“I felt I won the bout, but it was not so easy inside as Borges was really strong and well-prepared.”

The event in Venezuela is due to continue tomorrow with preliminary matches in the light flyweight, bantamweight, light welterweight, middleweight and heavyweight divisions.