SAN FRANCISCO -- Ryan Vogelsong will make his first start against the San Francisco Giants in 12 years Monday when the Pittsburgh Pirates open a three-game series against the National League West leaders.

Vogelsong, 39, played seven seasons for the Giants, including 2012 and 2014, when he started seven games and went 3-0 in the postseason as the club was winning a pair of World Series championships.

The 12-year veteran was allowed to leave as a free agent last winter, signing with the Pirates while the Giants were adding free agents Johnny Cueto and Jeff Samardzija.

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The Giants have since acquired a third new starter, Matt Moore, in a trade with Tampa Bay. The left-hander will oppose Vogelsong in the series opener.

Vogelsong last faced the Giants as a starter on Aug. 12, 2004, when he was the losing pitcher for the Pirates in a 7-0 home loss. He allowed three runs on six hits in five innings that day.

He started a game for the Pirates at AT&T Park in San Francisco earlier that season, limiting the Giants to two runs on eight hits over six innings in a 4-2 win.

He did not get a decision in that game, and has gone 0-1 with a 5.74 ERA in four career appearances (three starts) against the Giants.

Vogelsong went 48-49 with a 3.93 ERA over two stints with the Giants that covered all or parts of seven seasons. He started 132 games for San Francisco.

"He's never a foe; he's someone we're competing against," Giants right fielder Hunter Pence said of his former teammate. "I'll always be a fan of Ryan Vogelsong. You enjoy competing with him, and you're grateful for the honor to compete against him."

The right-hander will be making his third start (fifth appearance) this season for the Pirates. He's gone 1-2 with a 2.67 ERA, which would be a career-low if he were able to finish the season with it.

Vogelsong recorded his best season ERA as a Giant in 2011, when he made the NL All-Star team en route to a 13-7 record and 2.71 ERA.

He has pitched well for the Pirates since joining the starting rotation in August following the club's trade of Francisco Liriano to the Toronto Blue Jays. He's allowed just one earned run in 12 innings against Atlanta and San Diego, although the Pirates lost both games, 5-2 to the Braves and 4-0 to the Padres.

"It's no secret that I feel more comfortable (starting)," said Vogelsong, who has been used both as a starter and a reliever by the Giants and Pirates in his career. "For some reason, when I start, I feel like my stuff is better."

The Pirates flew to San Francisco on Sunday night on the heels of taking two of three from the Giants' NL West rivals, the Los Angeles Dodgers.

Like Vogelsong, the Giants' Moore has been the victim of a scarcity of run support. He has yet to record a win for San Francisco in two starts since the trade despite allowing a total of just four runs on six hits in 12 innings at Philadelphia and Miami.

The Giants have split those games, beating the Phillies 3-2 and losing to the Marlins 2-0. Moore received a no-decision and a loss in those games.

The 27-year-old will be making his AT&T park debut Monday, and will be facing the Pirates for the first time in his six-year career.

The Giants are coming off a stunning, 8-7 loss to the Baltimore Orioles on Sunday, a game San Francisco led 7-1 in the seventh inning.