SCOTTSDALE, Ariz. -- Brad Miller and Michael Saunders launched two-run home runs in the first inning, setting the stage for a huge offensive day for the Mariners, who knocked off the Giants, 18-3, on Saturday at Scottsdale Stadium.

Ryan Vogelsong, still the only projected starter for the Giants to have allowed a run in the Cactus League, gave up four in the first. Vogelsong allowed seven runs (five earned) on six hits in 2 1/3 innings.

"I warmed up good, and I felt good in the bullpen," Vogelsong said. "We got out there, and I don't know if it was just the adrenaline kicked in a little bit."

His counterpart, Erasmo Ramirez, was much sharper in four scoreless frames for Seattle. Ramirez, who struck out four and allowed just one hit, is fighting to lock up a spot in the starting rotation -- a battle that has become wide open because of injuries.

"Everything was about being aggressive," Ramirez said. "I was just trying to throw strikes with whatever pitch I threw. That's the first thing [catcher John Buck] told me, just go ahead, go ahead, put that in your mind. Don't think about who is hitting, just think about what I call and throwing strikes. We need to get ahead, every hitter and every inning, and just continue being aggressive. And it worked."

The Mariners blew the game wide open with five runs in the third -- only one of which was earned. Seattle took advantage of two errors in the frame, including a sun-induced drop by left fielder Juan Perez, which allowed a run to score.

Endy Chavez added a two-out, two-run single one batter later. Saunders and Willie Bloomquist also had RBI hits in the frame. Fighting for a starting spot in the Mariners' outfield, Saunders went 2-for-3 with three RBIs.

The Giants finally broke through in the sixth with two runs on an Andrew Susac double. It came three batters after Ehire Adrianza had led off the frame with a double.

Seattle answered right back, though, as Dustin Ackley smashed a two-run triple to right and scored one batter later on an infield hit. He went 3-for-4 and is now hitting .500 this spring.

Up next: Three pitchers age 24 and under will start for the Giants in their two games on Sunday. Edwin Escobar gets the ball for the split squad that heads to Glendale to face the Dodgers at 1:05 p.m. PT (Watch on MLB.TV). Meanwhile, Madison Bumgarner will start for the Giants' other squad against the Giants Future Stars, led by top prospect Kyle Crick, in Scottsdale at the same time. Angel Pagan, Brandon Belt, Buster Posey, Hunter Pence and Pablo Sandoval are among the players making the trip to Glendale to face Dodgers ace Clayton Kershaw.