Romeo Santos and Usher show off their soulful voices on the bilingual duet 'Promise,' a new song from the Latin singer's upcoming solo debut album, 'Formula.'

Santos is already well-known to many music fans for his work with the group Adventura. He also captured a Billboard Latin Award last year.

The Bronx-born singer of Dominican and Puerto Rican descent sings in Spanish, serenading his lady by singing that her body is a jail. Normally such a statement might not be a compliment, but he adds that he's the prisoner in the jail and he never wants to leave.

'Promise' opens like a ballad, with slow piano and finger snaps during Santos' verse, but Latin guitar and percussion appear to brighten up the song when Usher chimes in for the first time.

The R&B star echoes Santos' sentiments, delivering the hook, "I’ll give you my heart girl, but you've got to promise / Promise you’ll hold me, touch me, love me way past forever."

'Formula' is likely to hit stores later this year. Santos and Usher have shot a music video for the song, which we can't wait to check out, assuming it's as seductive as the song itself.

Listen to Romeo Santos' 'Promise' Feat. Usher