diagonal: <Never won something important> Letelier won the Gran Torneio Internacional Unesco in 1954, supposed to be the strongest / largest closed international chess tournament in Montevideo after WWII, organized as a special event during the campaign of the UNESCO Montevideo resolution in support of the Esperanto language:https://en.wikipedia.org/wiki/Monte...
http://www.brasilbase.pro.br/foto05...
(picture of all participants)
1. Letelier Martner (CHILE), 2./3. Najdorf (ARG), Bernstein (RUS / then FRA), 4. Toran Albero (ESP), 5=. Trompowsky (BRA), including also the Swedish champion in 1954, Bengt-Eric Horberg, Lorenzo Bauzá, champion of Uruguay in 1945, 1950, 1951, 1954 and 1955, and Ronald Cantero, national champion of Paraguay in 1954, 1955, 1956, 1957, 1958, 1961, 1962 and 1965, all three finishing as joint 8th-10th out of 18 players, among them eight from the hosting nation Uruguay as it was common in those years (large fields of participants, some top competitors mixed with local fodder players, of course not comparable with the supertournaments of modern type - but nevertheless important for the development of chess).
René Letelier beat both GMs, Najdorf and Bernstein! Also at Unesco Montevideo, septuagenarian Ossip Bernstein showed a great game and victory over Miguel Najdorf: O Bernstein vs Najdorf, 1954