The 25-year-old has scored three goals in his first three appearances for his chosen country after only receiving citizenship a few weeks ago.

Barrios' mother is Paraguayan and the forward has chosen to represent them rather than the country of his birth, however he insists the decision was not made out of spite at not being called up by Diego Maradona.

"I am not angry with Maradona for not giving me a chance," he told Germany's Bild am Sonntag newspaper.

"Anyway, I took the first steps towards being able to play for Paraguay in October 2009.

"I am proud to be Paraguayan, thanks to my mother who was born in Asuncion. But I also have an Argentinian passport.

"It was not a tough choice at all - it is a pleasure! I am very happy to be in the squad and there is nothing more beautiful than that, and I am thankful to everybody who has supported me."

Barrios is looking to make a big impact on the World Cup after impressing with both of his two club sides to date.

The striker arrived in the Bundesliga backed by the recommendation of 49 goals in 53 games for Chilean side Colo Colo and he netted 19 times in his first season in Germany with Dortmund.

That has already attracted the interest of several top European sides and he is going to be under the microscope in South Africa where he believes Paraguay could be a major challenger.

"We could be the surprise of the World Cup," he said. "We have a good team, above all in the attack."

Paraguay meet Slovenia, New Zealand and Italy in their group and will be favourites, along with the World Cup holders, to progress to the next round.

And Barrios holds no fear of the Azzurri, who Paraguay meet in their opening match on June 14.

"Italy are the world champions and have a good team - they are a team who always do well in tournaments and I respect them, but that respect disappears when you are on the field," he said.