If you leave me now

Written and sung by Chicago bass player Peter Cetera, this ballad from the album Chicago X topped the Billboard Hot 100 on October 23, 1976, becoming the group's first number one hit. The song won two Grammy Awards and was so pervasive on US radio that listeners in New York could reportedly hear it playing on four different stations simultaneously, eventually selling 1.4 million copies in the United States by August 1978.