SAN FRANCISCO (AP) — Vance Worley tossed a four-hitter for his first career shutout, and the Pittsburgh Pirates pounded Madison Bumgarner early in a 5-0 win over the struggling San Francisco Giants on Monday night.

Worley (4-1) struck out three and walked one. His only other complete game came in a 7-2 win over the Giants on July 26, 2011, in Philadelphia.

Four players drove in a run off Bumgarner (12-8) in the first, and Josh Harrison hit his seventh homer in the second to provide all of Pittsburgh's pop.

Worley worked over hitters the rest of the way to hand San Francisco its fifth straight loss.

The Sacramento native was acquired from Minnesota on March 25 for a player to be named or cash. He spent time in extended spring training and with Triple-A Indianapolis before being thrust into Pittsburgh's rotation because of injuries.

Worley has made the most of his opportunities in the majors. He has a 2.54 ERA in eight appearances, including seven starts, and silenced an announced crowd of 41,794 at AT&T Park with the best performance of his career.

Pablo Sandoval single twice, including leading off the fifth for the first baserunner against Worley. Gregor Blanco hit a swinging bunt single in the sixth before being nabbed trying to steal second. And Hunter Pence's two-out triple in the ninth was the only other hit Worley allowed.

The Giants, who were just swept in a three-game home series by the Dodgers to fall out of first place in the NL West, were counting on their All-Star pitcher to help wash away their woes.

Instead, Bumgarner gave up five runs and six hits in four innings. He had allowed one run in 14 innings since the All-Star break and was coming off his best start of the season.

All that evaporated in a 41-pitch first. He allowed three hits, two walks and committed one of two San Francisco errors in the inning when he misfired to second trying to pickoff Andrew McCutchen.

Gaby Sanchez, Neil Walker, Gregory Polanco and Russell Martin each drove in a run in the first.

TRAINER'S ROOM

Pirates: Left fielder Starling Marte can come off the concussion list Wednesday but likely won't resume baseball activities until a few days after that.

Giants: First baseman Brandon Belt passed his concussion test, resumed working out and is expected to return early in the team's 10-game road trip that begins Friday at the New York Mets. ... Backup catcher Hector Sanchez failed his concussion test and said he will be out least another three days. ... Center fielder Angel Pagan (back) will go through his pregame workout routine Tuesday in Arizona, and if everything goes well the Giants will set a date for his rehab assignment.

ON DECK

Pirates: LHP Francisco Liriano (2-7, 4.18 ERA) looks for his second straight victory.

Giants: RHP Tim Hudson (8-7, 2.65 ERA) tries to stop his three-game home losing streak.