Abstract: A backup tong incorporates a self-tightening feature to securely hold a string of tubing stationary while a spinning tong rotates a joint of tubing. The string of tubing is aligned between a moveable jaw and a body jaw of the backup tong. The moveable jaw is journaled for movement about a cam axis that is parallel to the tubing wall. The cam axis is eccentric to a curved face of the moveable jaw so that as the moveable jaw is moved the distance between the jaws changes. Prior to operations of the spinning tong, an air cylinder moves the moveable jaw into contact with the tubing. Rotation is begun and the induced movement of the tubing wall adjacent the moveable jaw toward a backer adjacent the jaws also moves the moveable jaw face toward the backer, thereby tightening the grip of the jaws on the tubing until the tubing is held stationary. A bracket attached to the spinning tongs has a slot therein parallel to the tubing.