Buster Posey broke a sixth-inning tie with an RBI single and Steven Duggar capped a big game with a two-run double in a five-run seventh, propelling the San Francisco Giants to a 7-1 victory over the Oakland Athletics in the opener of a three-game interleague series Friday night in San Francisco.

Madison Bumgarner (3-3) pitched into the seventh inning and right-hander Reyes Moronta escaped a bases-loaded, no-out jam to protect a one-run lead, as the Giants prevailed in the first of six straight games they'll play against their San Francisco Bay Area rival sandwiching the All-Star break.

After Oakland's Chad Pinder hit his 10th home run of the season, a solo shot, in the fifth inning to offset a Giants run that scored on an Edwin Jackson balk one inning earlier, Posey looped a two-out single to score Duggar in the sixth to give San Francisco the lead for good at 2-1.

The A's had a chance to at least get even in the seventh when Stephen Piscotty singled before Matt Olson and Matt Chapman drew consecutive walks to end Bumgarner's night.

But Moronta came out of the bullpen to strike out Pinder, retire Jonathan Lucroy on a liner to third base and get Nick Martini on a grounder to shortstop to retain the 2-1 advantage.

Bumgarner allowed one run and three hits in his six-plus innings. He walked three and struck out five.

The A's Jackson (1-1) also worked six innings. He gave up two runs and four hits, walking three and striking out one.

The Giants busted the game open in the bottom of the seventh against the Oakland bullpen when Duggar lashed a double to the wall in right field to score Alen Hanson and Gorkys Hernandez, both of whom had singled to open the inning.

A sacrifice fly by Andrew McCutchen, run-scoring wild pitch by Santiago Casilla and RBI double by Posey then completed the five-run inning, opening a 7-1 advantage.

Duggar finished with two doubles, two RBIs and three runs scored for the Giants, who improved to 5-3 on their 10-game homestand.

Posey and Hanson chipped in with a pair of hits apiece for San Francisco, which evened its interleague record at 4-4.

Pinder's homer was one of just three hits for the A's, who had a six-game interleague winning streak snapped.

Oakland, which lost All-Star second baseman Jed Lowrie to a bruised leg in the fifth inning, had won 13 of its previous 16 games, including five of seven to start its 10-game trip.

--Field Level Media