Semien leads charge behind stellar Mengden

Semien leads charge behind stellar Mengden

SAN FRANCISCO -- Marcus Semien skied a three-run home run as part of a five-run second inning, and A's starter Daniel Mengden stymied the Giants' bats through 7 2/3 innings in Oakland's 8-3 Bay Bridge Series-opening win at AT&T Park on Monday.

Mengden looked like a seasoned pro in earning his first Major League victory. The rookie, making his fourth start, retired the first 13 batters he faced and only allowed one baserunner to reach scoring position before the eighth inning.

"He's done that every time," Semien said. "This was his best outing, but he's given us a chance every time. It's good that we came in with some hot bats and that's what got him the win."

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Mengden earns first MLB win

The A's became the latest club to have a big game offensively against Giants starting pitcher Jeff Samardzija in June. Samardzija has allowed six earned runs in three of his last five starts.

"Second inning, it got away from him," said Giants manager Bruce Bochy. "We paid for it."

Semien got the best of him, too, hitting his 15th home run of the season in the second and an RBI double that scored Yonder Alonso in the sixth to finish with a career high-tying four RBIs.

MOMENTS THAT MATTERED
High five: The A's gave Mengden three more runs in the second inning (five) than they did in his first three starts combined (two), jumping out to a commanding lead against Samardzija. Semien led the charge, collecting his career high-tying 15th home run of the season. The A's shortstop, who already has 39 RBIs this season after finishing with 45 last year, was one of four players acquired in the December 2014 deal that sent Samardzija to the White Sox. He's 6-for-13 in his career against the right-hander.

Semien's three-run home run

"He's just continuing to put up numbers," A's manager Bob Melvin said. "You look at shortstops -- are they defenders, are they offensive guys? He's both. He's turned himself into both. He's a true two-way player. I don't know how his name doesn't come up in potential All-Stars with those numbers. He continues to work hard. He's the first one here. He's out on the field with extra work every day. He wants to play every game; he has played every game. You can't say enough about Marcus Semien and how hard he works and has improved."

Giants bats go silent: Angel Pagan broke up Mengden's no-hitter in the fifth with a single, and Gregor Blanco drew a walk one plate appearance later. But Mengden forced both Ramiro Pena and Conor Gillaspie to fly out on subsequent at-bats to end the inning, concluding one of the few threats the Giants' offense created on the evening.

"[Mengden's] got good stuff," Bochy said. "He's got a unique delivery that creates deception. He came into this thing 0-3, but look at his games, he's been throwing the ball very well."

Gillaspie scores on wild pitch

Pitches he'd like back: Samardzija lost control of his command in the second inning Monday, leading to an early 5-0 deficit for the Giants. Khris Davis hit an RBI double off him, and Semien put the Giants behind by four runs two at-bats later with a three-run homer on an 0-2 slider.

Davis' RBI double

"That sinker in to Davis and that 0-2 slider to Semien, two pitches right there and you're in a 4-0 hole," Samardzija said. "I'd like to have them back.

"It's a mental mistake when you're 0-2 to Semien and you leave one over the plate." More »

WHAT'S NEXT
A's: Right-hander Kendall Graveman, who has turned in a 3.55 ERA in his last seven starts, takes the mound in Tuesday's 7:15 p.m. PT matchup with the Giants at AT&T Park. Graveman allowed four runs on seven hits in 1 1/3 innings in his only career start against San Francisco, on July 26, 2015.

Giants: Right-hander Albert Suarez will make just his second start at AT&T Park on Tuesday. Suarez has a 4.29 ERA in four starts since replacing Matt Cain in the Giants rotation.

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Jane Lee has covered the A's for MLB.com since 2010.

Justin Wise is a reporter for MLB.com based in the Bay Area.

This story was not subject to the approval of Major League Baseball or its clubs.