Lysy traveled to London in 1952, where he enrolled in the Silver School; soon destitute, however, he made ends meet by playing under a bridge near the Royal National Theatre.
Following a performance for UNESCO in Paris, he returned to Argentina in 1953, though a second opportunity in 1955 took him again to Europe, where he became the first South American artist to obtain a prize at the Queen Elisabeth International Music Competition, held that year in Brussels.
Following the awards ceremony, the Queen Consort Princess Lilian, gave Lysy a vintage violin, and later invited him to the Royal Palace of Brussels for a series of duets.
Narrowly skirting military conscription (mandatory in Argentina until 1994), Lysy was recommended by Menuhin for a Rockefeller Foundation grant, and he rejoined his benefactor in Gstaad (becoming his first and only personal pupil).
Menuhin arranged performances for Lysy with consular figures in classical music such as cellist Pablo Casals, pianist Benjamin Britten, and conductor Nadia Boulanger.