By Matthew Harrington

OAKLAND, Calif. – A bug is rapidly sweeping the Oakland Athletics clubhouse and every starting pitcher seems to have come down with it. It isn’t a case of the flu, but an epidemic of quality starts, with the latest “victim” to succumb being Jesse Chavez.

“It’s contagious,” said Chavez. “Yesterday, watching Jeff Samardzija pitch, I just wanted to feed off that. As a team, we feed off that. We’re playing good baseball. We’re happy to be home.”

The A’s right-hander matched a career-high in strikeouts (nine) over six shut-out innings in a 5-0 win against the San Francisco Giants at O.Co Coliseum Monday night. The win in the opener of the 2014 Bay Bridge Series marks the fifth-straight win for the A’s (56-33), who swept one of the American League’s best in the Toronto Blue Jays in a four-game set over the weekend. A’s starters allowed three runs over 27 innings of work in the quartet of outings.

“I just want to hold down this spot for what happened earlier in the year,” said Chavez. “Whatever role they ask of me, I’ll do it. I’m just looking forward to being a part of this team.”

The decision for Chavez (7-5, 3.06 ERA) also marks a swing towards the early-season progress that had the reliever-turned-starter in the running for American League pitcher of the month in April. Chavez was 2-4 with a 4.08 ERA over his last eight starts coming in to Monday night, including a five-inning, five-run loss at Detroit in his most recent start last Wednesday.

“The last two starts, with two strikes I was over the plate a little bit,” assessed Chavez on his recent struggles. “My main focus was finishing the at-bat if I got ahead.”

Fernando Abad pitched 2/3 of an inning of scoreless relief; Dan Otero did his part with 1 and 1/3 frames without a run. Ryan Cook fired off a 1-2-3 top of the ninth inning to wrap up the game. In total, A’s pitchers scattered only five hits to the San Francisco offense. The Giants left seven runners on base, while Oakland stranded nine.

Craig Gentry represented the first A’s run of the night on a John Jaso ground-out in the fifth inning to snap Giants Starter Ryan Vogelsong’s 18 and 2/3 innings scoreless streak in interleague play. An inning later, Alberto Callaspo provided the crushing blow, greeting newly-inserted reliever Juan Gutierrez with a one-out, two-run double. Callaspo took the first offering from Gutierrez, a 92 mile-per-hour fastball, into the gap in right-center to plate Josh Donaldson from third base and Jed Lowrie from first. Vogelsong (5-6, 3.92) was charged with all three runs, and ultimately, the loss after his five and 1/3 innings of work.

Lowrie chased Vogelsong earlier in the inning, singling on a first-pitch delivery to put runners on the corners after Donaldson was controversially hit by a pitch to open the inning. Replay showed that the ball hit Donaldson’s fingers near the knob of the bat, sparking debate from Bruce Bochy. The Giants manager already burned his challenge when officials upheld a hit-by-pitch of Craig Gentry in the bottom of the fifth.

“It was originally called a foul ball,” said A’s manager Bob Melvin. “Once (home plate umpire Paul Nauert) saw his hand, he changed the call around.”

“It hit the small pinky, the pinky knuckle,” said Donaldson. “He did the right thing. I have to give him some credit. When I heard it, it sounded like it hit the bat, but obviously I felt my hand hurting. I knew it hit my hand. He did the right thing, looked at my hand, saw it was swelling. He asked if I swung. I told him I felt like I didn’t.”

A couple of seventh-inning errors from Giants shortstop Brandon Crawford put Jaso and Yoenis Cespedes on second and third with no outs, setting up a Brandon Moss sacrifice fly off Gutierrez for a 4-0 lead. Donaldson, the starting AL all-star third baseman by way of fan vote, knocked Gutierrez out of the game on a laser up the middle to score Cespedes for the A’s fifth and final run of the night.

The sold-out crowd of 36,067 saw Oakland continue its dominance of San Francisco in the East Bay. Oakland has taken 10 of the last 12 games against their Northern California foes at the Coliseum.

“It’s always fun,” said Chavez of playing in the friendly rivalry. “It’s good baseball. It’s two good teams going at it. I think that’s good baseball.”

While the A’s continue to trend upward to the best record in the Major Leagues, the Giants have scuffled to one of the worst margins of victory in the league. Over the last 26 games, San Francisco (49-40) has gone 7-19 after winning 42 of the first 63 games of the season.

The black and orange send All-Star starter Madison Bumgarner to the mound Tuesday looking to split the two-game series in Oakland before the interleague rivalry series shifts to AT&T Park for a pair starting Wednesday. Oakland hands the ball off to its ace, Sonny Gray to sweep the first half of the home-and-home.