On the play, Ben Zemanski fired a free kick from the right side of the pitch into the center of the box. Portland goalkeeper Troy Perkins charged out to make the stop, but collided with Califf, whose header sailed past him into an empty net.
Chivas (7-8-5), which saw its four-game unbeaten streak snapped last week in a loss to the Los Angeles Galaxy, remained in sixth place in the Western Conference following the Galaxy's victory over Dallas earlier Saturday.
Portland (5-12-4), meanwhile, sustained a fifth straight league defeat.
18-year-old elf alleges mall Santa pinched her buttocks on the job
Caroline Berg Eriksen: Soccer player's wife triggers debate with post-birth selfie