Jason Vargas pitched seven solid innings and the Seattle Mariners sent Boston to its season-worst seventh straight loss, beating the Red Sox 4-1 Monday.
The Red Sox fell to 0-7 on their road trip and have been outscored 58-16 in that span.
Vargas (14-9) allowed one run and six hits, walked no one and struck out five. He is the first Mariners pitcher other than Felix Hernandez to win at least 14 games since 2003.
Vargas, who leads the staff in wins, was coming off two sub-par outings in which he gave up a combined 11 runs and 15 hits in 8 2-3 innings.
Tom Wilhelmsen worked the ninth to pick up his 23rd save in 26 opportunities.