By JANIE McCAULEY
AP Baseball Writer
SAN FRANCISCO (AP) — Buster Posey homered in the first inning and scored the go-ahead run on an error in the third, and the San Francisco Giants beat the San Diego Padres 6-1 for their ninth straight victory a day after becoming the first team in the big leagues to clinch a playoff berth. Brandon Belt and Darin Ruf each hit run-scoring doubles and Tommy La Stella added an RBI single to back Anthony DeSclafani, who won for the first time in five starts since defeating Colorado on Aug. 13. The pitcher allowed six earned runs over his previous 14 2/3 innings.