(Photo credit: Stephen Brashear-USA TODAY Sports)

Entering the final day of the regular season, this is what is known: The Texas Rangers are headed to the American League playoffs while the Seattle Mariners, their Sunday opponent, are not.

The Rangers defeated Seattle 6-1 Saturday as Andrew Heaney pitched 4 1/3 scoreless innings in a spot startand Jonah Heim drove in three runs.

That clinched at least a wild-card berth for the Rangers (90-71), who will make their first postseason appearance since 2016.

"This is what I came back for, and there's nothing like it," said Rangers manager Bruce Bochy, in his first season in the Texas dugout following a three-year retirement. "It's been some kind of ride so far, and we've got a lot of work to do, but to be in this moment right now, these are memories you never forget, and for these guys I couldn't be happier."

After the game, members of both teams kept their eyes on televisions in their respective clubhouses at T-Mobile Park, pulling for the Arizona Diamondbacks to rally past the Houston Astros.

It didn't happen, with the Astros holding on for a 1-0 victory and clinching a spot in the playoffs.

That outcome eliminated the Mariners (87-74).

The Rangers will head into Game 162 with a one-game lead on the Astros in the race for the AL West title. The Rangers can clinch the division and the No. 2 seed in the league playoffs with a victory against Seattle on Sunday or a Houston loss.

"We're still trying to win this division," Bochy said while holding a bottle of champagne. "But to get there you work too hard from spring training to pass this up. You got to enjoy it. You got to celebrate."

It was a big transformation for the Rangers, who won just 68 games last season and finished 38 games behind the Astros in the AL West.

"To come from where we did last year to make the playoffs is extremely exciting. That's why we're celebrating tonight," Texas shortstop Corey Seager said.

Last year, the Mariners snapped a postseason drought that dated to 2001. But this time they fell shy on the final weekend of the regular season for the second time in three years.

There was some frustration among Mariners players that their team did little at the trade deadline while the Rangers made several moves to bolster their roster, and that still lingered on Saturday.

"We got to commit to winning," Seattle catcher Cal Raleigh said. "We have to commit to going and getting those players you see other teams going out, going for, getting big-time pitchers, getting big-time hitters, and we have to do that to keep up."

Mariners All-Star Julio Rodriguez took the loss hard, especially as he had just one hit in 21 plate appearances on the crucial season-ending homestand.

"I could have been better," Rodriguez said. "There is no other way around it. And I take that on myself. I prepared and everything, but it just didn't happen. It didn't happen for me. It's not the way that I wanted it, but it is what it is."

The Mariners will go with George Kirby (12-10, 3.46 ERA) on the mound Sunday against fellow right-hander Dane Dunning (12-6, 3.72).

Kirby is coming off six scoreless innings Tuesday in a 6-2 victory against Houston.

Kirby is 3-0 with a 1.52 ERA in five career starts against the Rangers. He beat them 5-0 on May 9 in Seattle, pitching seven scoreless innings and striking out nine.

Dunning is 3-1 with a 4.42 ERA against the Mariners in seven career starts. This season, he is 2-0, giving up six runs in 11 1/3 innings.