In bossa nova, many melodies and rhythms are strongly “syncopated”, i.e. shifted against the basic pulse. This means not just displaced by a quarter note, but in the rhythmic subdivisions of eighth or sixteenth notes. It is therefore often difficult to execute these rhythms precisely.
A case in point is the first four bars of Antonio Carlos Jobim’s “Desafinado“, as in this arrangement by Quincy Jones. The accented phrasing of the horn section clearly shows how the melody is displaced against the groove.