in 1952, at the age of 32, masselos played the brahms piano concerto in d minor in his first appearance with the new york philharmonic orchestra, led by dimitri mitropoulos. this impressive debut was the first in a long line of appearances with major orchestras which also included the new york philharmonic under pierre monteux and leonard bernstein, the montreal symphony under otto klemperer, the london philharmonic under bernard haitink, the american symphony orchestra under leopold stokowski, the philadelphia orchestra under eugene ormandy, and numerous others.