OAKLAND, Calif. (AP) -- Leave it to none other than Felix Hernandez to steal away some nice momentum from the Oakland Athletics.
The Seattle ace was at it again Saturday in the Oakland Coliseum, tossing seven scoreless innings in the Mariners' second straight victory over the AL West-leading A's in a 4-0 win.
"Yep, it was typical, boring Felix. His change is moving, his cut fastball is sinking," said Oakland catcher John Jaso, who caught King Felix's perfect game last season while with the Mariners. "It's tough to get comfortable in the box."
And Henry Blanco? Hardly typical.
Making his Mariners debut four days after the Blue Jays released him, Blanco hit a sixth-inning grand slam to break a scoreless tie and give Venezuelan countryman Hernandez all the offense he needed against A. J. Griffin (5-6) and the A's.
The 41-year-old Blanco, a .184 hitter with no home runs coming into the game, was a most unlikely candidate to provide the decisive hit for Seattle. The Mariners signed him Friday, then he became the oldest Seattle player ever with a slam.
"I was just trying for weak contact and Henry was looking for a well-placed fastball and he hit it," Griffin said. "I watched the video and the pitch went right where Jaso set up, up and in. At the end of the day it's four runs on one pitch and when you're facing Felix, every run counts."
Griffin (5-6) dropped to 0-3 over his four-start winless stretch. The right-hander allowed four runs and eight hits in six innings, struck out three and walked two.
Mariners manager Eric Wedge wrote Blanco into the lineup right away - and it didn't hurt Blanco had previously caught Hernandez in the bullpen for the World Baseball Classic.
"Talk about going up there ready to hit, bases loaded, he goes up there ready to hit and hit it a long way," Wedge said.
Hernandez (8-4) struck out five of Oakland's initial eight batters and seven through four innings on the way to eight Ks in seven scoreless innings. He improved to 15-6 in the rivalry spanning 28 career starts.
Michael Morse had two doubles among his three hits all off Griffin, including one in the sixth before Blanco's drive stayed just inside the left-field foul pole.
Blanco's only other grand slam came with Milwaukee more than 13 years ago - on May 12, 2000, off Pittsburgh's Jason Schmidt. It was the fifth-longest gap between grand slams dating back to 1900, according to information provided by the Mariners from the Elias Sports Bureau - 13 years, 34 days.
Blanco's slam at 41 - he turns 42 on Aug. 29 - topped one by Raul Ibanez earlier this season accomplished at 40 years, 347 days.
"That's pretty good. We'll I've got it now," Blanco said, smiling.
Hernandez received a big defensive assist to end the fifth and save a run.
Jed Lowrie doubled leading off the inning and advanced on Seth Smith's flyout to center. But Chris Young flied into a double play in which right fielder Endy Chavez threw Lowrie out at home to keep the game scoreless. Lowrie didn't even touch the plate.
"I called him out," Hernandez quipped.
That was Oakland's best opportunity.
"You have to take a chance there with Felix, that was our only chance to score a run right there," A's manager Bob Melvin said.
With Coco Crisp aboard on a one-out single in the sixth, Hernandez got Jaso to line into a double play at first that caught Crisp off the bag. The A's also grounded into an inning-ending double play in the seventh with runners on first and second.
Suddenly, Seattle has a chance to sweep the first-place A's on Sunday after Oakland took three in a row from the New York Yankees before this series began, including a 3-2, 18-inning victory Thursday.
The Mariners snapped Oakland's 11-game home winning streak at the Coliseum on Friday night, then put together another fine performance to back their ace. The A's have lost their first series in the last 10 over the past month.
Hernandez allowed five hits and walked one to improve to 22-7 with a 2.70 ERA lifetime in 39 career starts in June. Seattle starters are 5-1 with a 0.94 ERA - 6 earned runs in 57 1-3 innings - since June 7 and have gone six straight starts of at least seven innings.
Charlie Furbush and Yoervis Medina each pitched an inning of relief to finish the Mariners' six-hit shutout.
Still, Blanco provided the highlight of the day.
"You knew in a game like this, when there are two good pitchers who both have their stuff, it's going to be one swing that makes the difference," Jaso said.
Notes: Young earned a second straight start for the A's a day after going 3 for 3 with an RBI and walk - but he had never faced Hernandez previously and went 0 for 3 with a strikeout. ... A's 3B Josh Donaldson was back in there after missing Friday's game because of a strained right hamstring. He came out of Thursday's 18-inning win against the Yankees after the 15th. ... Crisp returned to the Oakland lineup playing center field and batting leadoff in his first start since bruising his heel Tuesday night against New York. He didn't move as well as usual. ... A's RF Josh Reddick had the night off. ... The series finale Sunday has the looks of a possible pitcher's duel with Oakland's Bartolo Colon (8-2) and Seattle's Hisashi Iwakuma (7-1). ... Announced first-pitch temperature was 56 degrees.