Pablo Sandoval went the opposite way for a walk-off home run to left field with one out in the 13th inning Tuesday night, sending the San Francisco Giants to their fifth extra-inning win in the last eight days, 5-4 over the visiting Chicago Cubs. After the Cubs had forced extra innings with single runs in the seventh and eighth to forge a 4-4 tie, neither team scored again until Sandoval, a switch-hitter batting left, launched a Brad Brach (3-3) pitch barely over the glove of a leaping Robel Garcia for his 12th homer of the season. Right-hander Sam Coonrod, promoted Monday from Triple-A, recorded his first major league win in just his fifth big-league appearance with a 1-2-3 top of the 13th, including strikeouts of Javier Baez and Kris Bryant.