WASHINGTON (AFP) — Jeremy Pena's solo home run in the 18th inning lifted the Houston Astros over Seattle for a Major League Baseball playoff sweep while Philadelphia ousted defending champion Atlanta on Saturday.

Pena's blast after the most scoreless innings in MLB playoff history gave the Astros a 1-0 victory over the Mariners and a 3-0 sweep of their best-of-five American League division series matchup.

Houston reached the best-of-seven American League Championship Series for a sixth consecutive year and will face either the Cleveland Guardians or New York Yankees.

Cleveland rookie Oscar Gonzalez hit a two-out, two-strike single with the bases loaded in the ninth inning to drive in two deciding runs in a dramatic 6-5 victory over the visiting Yankees.

"I just wanted to put the ball in play. Thank God I got the results," the Dominican said through a translator.

"Then I was just waiting for the guys to score and celebrate."

The Guardians swiped a 2-1 series lead with the chance to advance by winning at home on Sunday.

In the National League, Philadelphia defeated Atlanta 8-3 to win their series in four games.

J.T. Realmuto hit an inside-the-park home run while Brandon Marsh smacked a three-run homer and Bryce Harper added a solo homer for the Phillies.

Philadelphia advanced to an NL finals showdown against either the Los Angeles Dodgers or San Diego Padres to decide a World Series berth.