SAN DIEGO -- The San Francisco Giants defeated the San Diego Padres, 1-0, in 12 innings in San Diego's home opener on Thursday.

San Francisco outfielder Justin Maxwell's two-out, pinch-hit single drove in shortstop Brandon Crawford for the game-winner. Crawford reached on shortstop Clint Barmes' error, when he dropped a pop fly while backpedalling into left field.

George Kontos (1-0), the sixth of the Giants' seven pitchers, got the win after working 1 2/3 innings. Santiago Casilla notched his third save in as many chances.

Nick Vincent (0-1) took the loss.

The Padres, who had runners at third base in the ninth and 10th innings, squandered an opportunity in the ninth when left fielder Justin Upton reached after McGehee misplayed his grounder for an error. Then second baseman Jedd Gyorko contributed a two-out single. But Barmes grounded out to Crawford.

Angel Pagen opened the Giants' ninth with a triple to right-center off new Padres closer Craig Kimbrel. It came after Pagen and Padres catcher Derek Norris exchanged words, which led plate umpire Greg Gibson to warn both benches. Catcher Buster Posey then walked.

But Kimbrel got Crawford to pop up to shortstop Alexi Amarista. McGehee then grounded to Amarista and he started an inning-ending double play.

The Giants left two runners in scoring position in the eighth after a single by right fielder Gregor Blanco and a walk to pinch-hitter Matt Duffy; both advanced on left fielder Nori Aoki's fly ball to right. But second baseman Joe Panik popped up to third for the final out.

Padres first baseman Yonder Alonso walked to start the seventh and when starter Tim Hudson allowed a one-out single to Amarista, he was pulled for reliever Jeremy Affeldt. He got pinch-hitter Yangervis Solarte to ground into an inning-ending double play, the fourth the Padres hit into.

The Padres got runners on the corners with one out in the sixth inning, after center fielder Wil Myers singled and right fielder Matt Kemp walked. But Upton erased Kemp on a grounder and third baseman Will Middlebrows flied out to right.

In the Padres' fifth, Middlebrooks doubled and moved to third base on Alonso's single to right. Gyorko then hit what looked to be a run-scoring base hit up the middle.

But Crawford made a diving snag and flipped the ball with his glove to second baseman Joe Panik. His relay to first baseman Joaquin Arias was in time to retire Gyorko, the second double play he hit into in two at-bats.

Amarista walked, but pitcher Odrisamer Despaigne grounded out to end the inning to strand Middlebrooks to third.

Padres starter Ian Kennedy was lifted for Despaigne after throwing his 33rd pitch to Aoki in the third inning. Kennedy, who was 13-13 last year with a career-high 207 strikeouts, strained his left hamstring.

Designee, who lost his bid to become the team's fifth starter in training camp, was solid. He pitched 4 2/3 innings scoreless and hitless innings. He retired all 14 batters he faced.

NOTES: Giants RHP Jake Peavy is on track to start Sunday in San Diego against his former team. Peavy, who won the 2007 National League Cy Young Award with the Padres, was scratched from his first start because of a sore back. ... After a dreadful spring offensively, the Giants came alive in their opening series with the Diamondbacks. The Giants hit .330 (37 for 112) with a gaudy .509 slugging percentage. ... 1B Brandon Belt (groin) remains day to day. ... Padres manager Bud Black said RHP Josh Johnson was throwing a bullpen session. Johnson didn't pitch last year because of an arm injury. ... C Derek Norris sprained an ankle Wednesday night but was in the lineup. ... The Padres debuted their new video board, which is the largest in the National League.