Matt Olson hit a three-run homer in a five-run first inning and the Oakland
Athletics went on to defeat the host Seattle Mariners 7-4 on Sunday afternoon.
Marcus Semien and Ramon Laureano also homered for the A's, who took two of three games in the series and have won nine of their past 12 entering the All-Star break.
Oakland right-hander Daniel Mengden (4-1) won his third straight start, allowing three runs on six hits in 5 1/3 innings. He didn't walk a batter and struck out two. Right-hander Liam Hendriks pitched the ninth for his fifth save.
Omar Narvaez went 4 for 4 with two home runs and four RBIs for the Mariners, who have lost eight of their past 10.
Mariners right-hander Matt Carasiti (0-1), who was being used as the opener for lefty Wade LeBlanc, struggled in the first inning, retiring only one of the six batters he faced.
Semien led off with an infield single off the glove of Mariners shortstop J.P. Crawford and Robbie Grossman walked. Following a wild pitch that advanced Semien to third, Olson hit a 2-2 pitch over the wall in right-center field, his 19th home run of the season.
After Khris Davis was called out on strikes, Mark Canha doubled to right field and Ramon Laureano reached on an infield single, sending Canha to third. That was it for Carasiti, with LeBlanc summoned from the bullpen.
Chad Pinder lined LeBlanc's first pitch into left field for a run-scoring single, with the ball rolling between the legs of outfielder Dylan Moore and all the way to the wall, allowing Laureano to score from first on the fielding error to make it 5-0.
Semien led off the second with a home run to left-center field, his 14th.
The Mariners got a run back in the bottom of the inning on Narvaez's one-out solo shot to right field.
Seattle made it 6-2 in the fourth as Domingo Santana led off with a double, moved to third on an infield out and scored on Narvaez's single to left.
The Mariners tallied in the sixth as Crawford led off with a ground-rule double and scored on Narvaez's one-out single off left-hander Ryan Buchter.
Laureano homered with one out in the eighth off right-hander Matt Wisler, who was making his Mariners debut.
Narvaez capped the scoring in the eighth with another solo homer, his 14th, to center field.