Further fine showings followed. At Mar del Plata 1957, he scored 10.5/17 for sixth in a high-class field which included world #3 Paul Keres, beating Soviet Grandmaster Alexander Kotov. He scored 9.5/11 to win at São Paulo 1957, finishing ahead of perennial Argentine champion Miguel Najdorf. He qualified out of Rio de Janeiro 1957, the South American Zonal, for the 1958 Interzonal tournament, tying for second with 11.5/15, and again topping Najdorf, who failed to qualify. He earned the International Master (IM) title in 1957 for this result. At Mar del Plata 1958, he tied for third with 9.5/15. Then came the Argentine Championship of 1958, where his 11.5/17 earned him fourth place. In 1958, he also won the CAVP tournament in Buenos Aires.