At Buenos Aires 1965, Sanguineti scored 6.5/11 to end fourth, and he won the 1965 Argentine Championship with an impressive 16/21. Mar del Plata 1965 was again very strong, with Najdorf, Leonid Stein, and Yuri Averbakh in attendance, and Sanguineti could only manage eighth place with 8.5/15. The next year at Mar del Plata he scored 7.5/15 to finish tied seventh. For the Havana 1966 Olympiad, Sanguineti was again on board four for Argentina, and performed superbly with 11/15. Argentina finished fifth.