Kumar, who won the Light welterweight event on home soil at New Delhi 2010, was involved in a scrappy affair with the Puerto Rican but managed to prevail 2-1 on the judges scorecards.

De La Rosa put in an aggressive performance and was repeatedly warned for headbutting, according to Kumar's coach Gurbax Singh Sandhu.

"It was a brilliant performance by Manoj," Sandhu told the Press Trust of India.

"Danielito was cautioned repeatedly for head-butting dangerously and it was to Manoj's credit that he kept his composure.

"Especially in the third round, Manoj got his strategy perfectly right by fighting from the long range."

Elsewhere in the same category, Gary Russell of the United States breezed to a unanimous win over Viktor Petrov of the Ukraine, while Richardson Hitchins moved a small step closer to securing a Rio 2016 place for Haiti by beating Iran's Haidi Makouei.

In the flyweight division, there were wins for Villiam Tanko of Slovakia, who ousted Aref Mohammad of Afghanistan 3-0, and South Korean Inkyu Kim as he beat Hamza Touba of Germany by split decision.

At middleweight, Nick Frese of Thailand made light work of Jose Virula Lopez of Guatemala with a comfortable unanimous success.

He will be joined in round two by Japan's Makoto Takanashi, who was able to sweep aside Edin Avcic of Austria, also by unanimous decision.

A total of 39 Olympic places are on offer during the tournament in Baku, which runs until June 25.

The top five boxers at flyweight, bantamweight, lightweight, light welterweight, welterweight, middleweight and light heavyweight will all earn Olympic berths.

In addition two spots are available at light heavyweight, with only the winners in Baku progressing at heavyweight and super heavyweight.