Justin Smoak was frustrated as soon as he hit a chopper to first base in the 10th inning, sure he had stranded the potential go-ahead run at third base. But the ball bounced just high enough to glance off Daric Barton's glove to give the surging Mariners another win. Smoak's two-out RBI single helped Seattle overcome a shaky start by ace Felix Hernandez to win for the 10th time in 12 games, 6-4 over the Oakland Athletics in a doubleheader opener on Wednesday. "It's baseball, and that's what happens when you go on good streaks," Smoak said. "Stuff like that happens." Corey Hart and Mike Zunino hit solo homers off Dan Straily, and the Mariners got the win in a game in which Hernandez failed to strike out a single batter for the first time in nearly six years. Brandon Moss hit an RBI triple that capped a three-run seventh against Hernandez, but the A's could not hold a late lead and have lost six straight home games for the first time since September 2007. "It's frustrating," A's manager Bob Melvin said. "We actually had good at-bats against (Hernandez) from the first inning on. Squared some balls up and hit some balls hard at people on top of it. Our approach was really good on him today. We just let it slip away in the later innings." Michael Saunders led off the 10th with a single off Ryan Cook (0-1), stole second and went to third on a sacrifice bunt by Stefen Romero. After an intentional walk to Robinson Cano, Cook struck out Hart before leaving with a strained right forearm.