Coming off two straight shutouts, Montgomery (4-2) gave up one run and six hits in 5 2/3 innings. He walked one and struck out two.
Montgomery retired the next six batters, then got some help from Seattle's defense before leaving with two on and two outs in the sixth.
Fernando Rodney pitched the ninth for his 16th save.
The Mariners announced before the game that manager Lloyd McClendon will miss Seattle's upcoming series against Detroit to attend the funeral for his younger sister in Indiana.