Samba Em Prelúdio is in … time
4/4 time - which can sound like two minim beats in a bar instead of four clearly defined crotchet beats. This is a feature of the bossa nova.
The opening 3-bar introduction is in…
Free time
whereas verse 1 is very slow with a lot of…
Rubato
The music then quickens to a bossa nova tempo (about 140 bpm) in…
verse 2 before returning to free tempo in the coda.
The rhythms are complex throughout the song because of the amount of syncopation, triplets and rests.
Cross-rhythms between the voice and guitars are heard throughout the song.