With Minnesota trailing 2-1, Dozier followed consecutive singles by Aaron Hicks and Eduardo Escobar by sending a curveball from Roenis Elias (3-3) into the seats in left field. It was Dozier's 11th homer of the season.
Michael Saunders had a homer and two RBIs for Seattle.
Deduno (1-2) struck out four, allowed two hits and retired 18 of the 23 batters he faced. Both of Seattle's runs off Deduno came in the third inning after James Jones scored Brad Miller with his first career triple. Jones then scored on Saunders' sacrifice fly to give the Mariners a one-run lead.
But Deduno was otherwise solid, working efficiently through Seattle's lineup over the next three innings while Elias struggled with his control. Elias allowed six hits and one walk in seven innings, but he also hit a batter, and had a wild pitch and a balk in the second inning.
Seattle pulled to 4-3 in the eighth when Saunders hit a solo homer off Jared Burton. Corey Hart doubled two batters later, but Burton got Kyle Seager swinging to end the threat. Glen Perkins worked the ninth for his 12th save in 14 chances.