The Thai boxer, arguably one of the most high-profile names competing in the event at the Jose Maria Vargas Dome, powered to a comfortable unanimous win against his German APB opponent.

Ruenroeng was awarded the bout on all three judges’ scorecards and will next go up against Italy’s Carmine Tommasone.

The Italian maintained his pursuit of a Rio 2016 berth as he overcame Ukraine’s Oleh Dovhun, who represented the Ukraine Otamans during last season’s WSB campaign.

Elsewhere, Spain’s Youba Ndiaye Sissokho produced one of the performances of the day as he beat Serhii Bohachuk of the Ukraine in the light welterweight division, progressing thanks to a surprisingly straightforward unanimous win.

WSB light heavyweight Juan Carrillo of Colombia, who had a strong season for the Puerto Rico Hurricanes, delivered the first technical knockout of the tournament during his bout with Serbia’s Petar Maukovic.

In the same division, Jonathan Esquivel of the United States, who came into the competition in the Venezuelan city having won both his WSB contests for the USA Knockout, was also in good form as he ousted Bulgarian APB boxer Spas Genov.

Esquivel was another victor by unanimous decision and faces a stern test in the next round as he will take on former World Boxing Organisation interim middleweight champion Hassan N'Dam of Cameroon.

“I felt good in my opening bout and though I could have performed much better, all that matters is that I got the decision,” the American said.

"My tactics were to stay off the jab and keep it simple but explosive.

"I expect a more intense bout against my Cameroon opponent, but I’m sure I will control the bout and get the win.”

The tournament is the only opportunity for professional boxers to qualify for the Rio 2016 Olympic Games.

It follows a controversial ruling, passed unanimously at the International Boxing Association (AIBA) Extraordinary Congress on June 1, which opened up the Olympic boxing competition to professionals for the first time.