Prior to dawn on 22 December, she took up patrol duties off San Fernando in the northern approaches to the gulf, and moved south. At 0411, she sighted an enemy destroyer and, at 04:24, she fired. Although the "fish" headed "right at" the destroyer, there was no explosion. At 04:26, a second destroyer appeared; and, the hunter became the hunted. "Saury" commenced evasive tactics in the relatively shallow waters of the gulf. Depth charges were dropped, but none within of the submarine. "Saury" continued on evasive courses, working her way to the northwest and out of the destroyer-patrolled area. By noon, she was clear. After dark, she moved back into the gulf, past the enemy patrol line between San Fernando and Cape Bolinao.