The San Francisco Giants won their ninth consecutive game Tuesday night, riding a home run from Buster Posey and a strong start from Anthony DeSclafani to a 6-1 victory over the visiting San Diego Padres.

Tommy La Stella, Darin Ruf and Brandon Belt also drove in runs for the Giants (95-50), who clinched a National League playoff spot on Monday night and continued pursuit of an NL West division title 24 hours later. San Francisco maintained its 2 1/2-game lead over the Los Angeles Dodgers (93-53).

The loss was a season-worst fifth straight for the Padres (74-70), who have fallen behind both the St. Louis Cardinals (75-69) and Cincinnati Reds (75-70) in the race for the second NL wild-card spot.

Posey's solo shot, his 18th homer of the season, came on Padres starter Jake Arrieta's ninth pitch of the game and opened the scoring.

The Padres drew even in the third on a double by Jurickson Profar, a Jake Arrieta sacrifice bunt and a Trent Grisham RBI infield out before the Giants did the rest of the night's scoring.

Posey scored from third on an errant pickoff throw by Arrieta in the bottom of the third, La Stella singled home Steven Duggar in the fourth and Ruf doubled home Brandon Crawford in the seventh as the Giants continually increased DeSclafani's cushion, going up 4-1.

The right-hander limited San Diego to three hits and one run in 6 2/3 innings. He walked one and struck out three.

DeSclafani (12-6) won for the first time since Aug. 13. He had been 0-1 with a 3.86 ERA in three previous starts against the Padres this season.

Tony Watson, Tyler Rogers and Camilo Doval worked the final 2 1/3 innings, retiring all seven men they faced.

Making his third start for the Padres, Arrieta (5-13) took the loss, charged with three runs on five hits in 3 2/3 innings. He walked two and struck out three.

The Giants tacked on two insurance runs in the eighth on an RBI double by Belt and a throwing error by San Diego third baseman Manny Machado.

Posey scored twice, and he, La Stella and Belt had two hits apiece for San Francisco, which has won on each of the first two nights of the four-game series.

Jake Marisnick added a double for the Padres, who were out-hit 10-3.