PHOTOS BELOW ...
Dustin Ackley and Abraham Almonte each homered in the fifth to provide plenty of run support for Hernandez, who held Oakland scoreless over eight efficient frames before Jed Lowrie led off the ninth with a drive over the wall in right-center field.
Brandon Moss scorched Hernandez's next offering back up the middle for a single, but after a brief meeting on the mound, Hernandez bounced back to fly out Yoenis Cespedes, who pulled a pitch just foul deep down the left-field line before being retired.
With Hernandez at 101 pitches, closer Fernando Rodney entered from the bullpen and fanned John Jaso and Josh Reddick in succession to nail down his first save with Seattle.
Overall, Hernandez (2-0) scattered six hits and a walk over his outing. The right-hander hasn't taken a loss over his last 10 starts at O.co Coliseum.
Dan Straily (0-1) absorbed the hard-luck loss for Oakland after giving up three runs on six hits and a walk with seven strikeouts in six innings. Lowrie and Moss combined for four of the six hits for the A's, who claimed Thursday's series opener thanks to Coco Crisp's solo shot in the 12th inning.
Oakland failed to muster its first hit off Hernandez until the fourth, when Lowrie laced a single to center. Moss followed with a towering fly ball that eluded everyone in shallow center field to put men on second and third, but Hernandez fanned Cespedes on three pitches to end the frame.
Straily, meanwhile, stifled Seattle over the first four frames, striking out seven and yielding just two hits before succumbing to the long ball in the fifth.
Kyle Seager opened the frame with a double and Ackley followed two batters later with a drive into the seats in right-center field.
After Mike Zunino flied out to center, Almonte turned on a 1-0 fastball and launched it over the right-field wall for a 3-0 lead.
Crisp ripped a triple into the right-field corner with one away in the sixth, but Hernandez got Josh Donaldson to swing at a low sinker for strike three before inducing an inning-ending popout from Lowrie.
The series was scheduled to be four games, but Friday's contest was postponed due to poor field conditions ... Hernandez has gone 5-0 during his 10-start unbeaten streak at O.co Coliseum ... Seattle's pitching staff has allowed three runs or less in each of the team's first five games to extend the club record ... Oakland finished 0-for-6 with runners in scoring position and stranded six runners ... Rodney signed with Seattle in the offseason after spending the last two seasons as Tampa Bay's closer.
04/05 19:05:54 ET