Sergio Blanco Rivas and Estíbaliz Uranga Améraza were both former members of Mocedades, the group which represented Spain at the 1973 Contest with "Eres tú", Estíbaliz is in fact the sister of lead singer Amaya Uranga. Both "Eres tú" and "Tu volverás" were written by prolific Spanish composer and lyricist Juan Carlos Calderón.