 Roncero was included in a mid-week Pumas side to play South Africa A, that Marcelo Loffreda was using to determine part of his squad for the 2003 Rugby World Cup.He was included in the Pumas' 2003 Rugby World Cup squad, playing in matches against Namibia and Romania.He was capped five times for Argentina in 2004, including in a match against the All Blacks.