Dodgers starting pitcher Aaron Harang escaped a first-inning jam, but the Mariners scored twice in the second inning on four consecutive singles, the final one being a two-run hit by Franklin Gutierrez, continuing his production in the leadoff spot.
The Dodgers answered against former teammate Jon Garland with a run in the bottom of the second on a leadoff double by Andre Ethier and a one-out RBI grounder by Tony Gwynn.
Garland, on the comeback after missing all of 2012 with shoulder surgery, allowed the one run in three innings, as he battles for a starting spot as a non-roster invitee.
"Not too bad," Garland said after pitching his longest stint of the spring. "My arm is definitely coming around. I can definitely tell it's getting stronger as the outings are going. Nothing is tightening up between innings. So just good signs all around."
Harang, rumored to be on the trade block because of the Dodgers' starting pitcher surplus, was charged with the two runs on six hits in three innings.
Justin Sellers had two of the Dodgers' hits. Gutierrez, Jesus Sucre and Brendan Ryan each had a pair of hits for Seattle.
Up next: Clayton Kershaw starts for the Dodgers Sunday against Colorado on the road and he'll bring his bat with him. The Dodgers have used designated hitters for the first two weeks of games, but manager Don Mattingly said pitchers will start to get at-bats beginning with Kershaw, who hit .207 last year with 14 sacrifice bunts. Matt Kemp, who was designated hitter Saturday, will probably start in center field.