The Oakland Athletics clinched their first AL West title since 2013 on Monday night with an assist from the rival Houston Astros.

Houston lost 6-1 to the Seattle Mariners, ending its three-year reign as division champion. The A's were off Monday before opening an interleague series at Dodger Stadium on Tuesday.

Since last season ended, the slugging A's have emphasized the need to win the division given they won 97 games each of the last two years and lost the AL Wild Card game.

Oakland Athletics' Mike Minor pitches against the San Francisco Giants during the first inning of a baseball game in Oakland, Calif., Sunday, Sept. 20, 2020. (AP PhotoJeff Chiu)

Oakland Athletics' Mike Minor pitches against the San Francisco Giants during the first inning of a baseball game in Oakland, Calif., Sunday, Sept. 20, 2020. (AP PhotoJeff Chiu)

Oakland is in the playoffs for a third straight year and the sixth time in nine seasons. A's right-hander Mike Fiers was the whistleblower in the Astros' offseason sign-stealing scandal when he publicly called out his former club for cheating in an article published by The Athletic in November.

Houston won a majors-best 107 games last season and brought in veteran manager Dusty Baker to lead the way in 2020.

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Oakland Athletics center fielder Ramon Laureano catches a ball hit by San Francisco Giants' Brandon Belt for an out during the first inning of a baseball game in Oakland, Calif., Sunday, Sept. 20, 2020. (AP PhotoJeff Chiu)

Oakland Athletics center fielder Ramon Laureano catches a ball hit by San Francisco Giants' Brandon Belt for an out during the first inning of a baseball game in Oakland, Calif., Sunday, Sept. 20, 2020. (AP PhotoJeff Chiu)