(Photo credit: Sergio Estrada-Imagn Images)

Luis Castillo pitched seven strong innings and Josh Naylor smacked his first homer with the Mariners to help Seattle post a 3-1 victory over the Athletics on Monday night in West Sacramento, Calif.

Naylor had two hits and scored twice for the Mariners, who are three games behind the first-place Houston Astros in the American League West. Cal Raleigh notched two hits and an RBI and Ben Williamson produced two hits, one run and a big defensive play for Seattle.

Castillo (8-6) allowed one run and five hits. He struck out four and walked none to finish off a 4-1 July.

Andres Munoz worked around a leadoff single in the ninth to record his 24th save.

Brent Rooker had an RBI for the Athletics, who were coming off a four-game road sweep of the Astros.

A's starter JP Sears (7-9) gave up three runs (two earned) and five hits over 4 1/3 innings. He struck out six and walked three.

Athletics All-Star shortstop Jacob Wilson (left hand) sat out his third straight game.

Naylor led off the second inning with a homer to right-center off Sears. The blast came in his fourth game with Seattle since being acquired from the Arizona Diamondbacks.

A throwing error by Athletics first baseman Nick Kurtz helped the Mariners score a run in the fourth.

Naylor singled to start the inning. With Jorge Polanco up, Naylor took off for second before Sears headed home, and the left-hander tossed the ball to Kurtz. However, the ensuing throw by Kurtz was wild and went into left field as Naylor advanced to third.

One out later, Mitch Garver hit a sacrifice fly to center to score Naylor and make it 2-0.

In the fifth, Williamson doubled to left and scored on Raleigh's single to left, ending Sears' night.

The Athletics scored their lone run off Castillo in the sixth.

Luis Urias was hit by a pitch to start the frame, and he went to third on a one-out single to right by Kurtz. Rooker then hit into a fielder's choice to score Urias.

The Athletics threatened in the eighth as pinch hitter Colby Thomas drew a one-out walk against Gabe Speier. Matt Brash entered with two outs and gave up a single to Rooker and walked Shea Langeliers to load the bases.

Tyler Soderstrom then hit a grounder that third baseman Williamson dove for and gloved. Williamson raced to the bag and beat Rooker to end the inning.

--Field Level Media