By Jeremy Kahn

sfgate.com file photo: San Francisco Giants pitcher Madison Bumgarner on Thursday night at the Oakland Coliseum against the Oakland A’s hitting for himself, swinging for a double and going six plus innings for the win

OAKLAND-Madison Bumgarner became the first pitcher in 40 years to bat in an American League park, and what a performance by the lefty.

In his first at-bat, Bumgarner hit a double off the glove of Billy Burns in centerfield, which led to a six-run third inning and the San Francisco Giants defeated the Oakland A’s 12-6 before a sellout crowd of 36,067 at the Coliseum.

Following the Bumgarner double, Denard Span walked, then Angel Pagan tied up the game with a single to score Bumgarner and then Brandon Belt doubled. Instead of walking Buster Posey intentionally, Dillon Overton threw a pitch that Posey launched over the left-center field wall for his ninth home run of the season.

Bumgarner gave the bullpen much needed rest, as he went 6.1 innings, allowing four runs on seven hits, not walking a batter and striking out four on his way to ninth win of the season.

In those 6.1 innings of work, Bumgarner allowed two home runs, the one to Marcus Semien in the bottom of the first inning and then a two-run home run to Yonder Alonso in the bottom of the seventh inning. The Alonso was the first by a left handed batter since he allowed one to Scooter Gennett of the Milwaukee Brewers on Opening Day at Miller Park.

With the victory, the Giants are just the second National League team to reach 50 wins and the third in the major leagues. Both the Chicago Cubs and the Texas Rangers each have 51 wins.

On the very next pitch by Overton, Brandon Crawford hit his seventh home run of the season, as he was the last of six in a row to score against Overton.

Overton was able to get of the inning, as he struck out Mac Williamson, got Grant Green to strikeout and after a walk to Ruben Tejada, Bumgarner popped out to Jed Lowrie at second base to end the inning.

Things got worse for the A’s and Overton in the top of the fourth inning, as Span doubled and then scored on a Pagan double and that was it for Overton, as Bob Melvin replaced the left-hander with Andrew Triggs.

In just three innings of work, Overton went three innings, allowing seven runs on eight hits, walking three and striking out one. Overton saw his earned run average increase from 4.76 to 11.42.

It did not start good for Bumgarner, as he gave up to Marcus Semien with one out in the bottom of the first.

The Giants added four runs in the top of ninth, as Fernando Rodriguez allowed four runs on one hit, walking and no one.

Belt came up with the big hit of the inning, as he lined a double through the extreme shift.