NEW YORK – Before diving into the Yankees’ fortunate, 6-5 playoff opening win against the Kansas City Royals, who made the costlier missteps, let us re-introduce Luke Weaver, the pinstriped October surprise you didn’t know you needed.

A year ago, Weaver posted a 6.87 ERA as a Cincinnati Reds starter.

A month ago, having graduated into a valuable setup man, Weaver was on the brink of stepping into the closer’s void – not ideal timing for a win-now club trying to clinch the AL East.

Any ideas about a bullpen by committee were shelved by Weaver, who became a committee of one down the stretch and closed out Game 1 of the best-of-five AL Division Series.

After 10 years of knocking around the big leagues, Weaver was asked if he was built for this role.

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“Well, it’s sure not my size,’’ said Weaver, a right-hander with the wry take of an oft-centered lefty. “Even though I feel like being wiry is a very internally strong foundational attribute.’’

Yankees stumble, but survive due to Royal mistakes

Weaver’s neat, four-out save came with three strikeouts – including the Bobby Witt Jr., who somehow went 0-for-5 at Yankee Stadium, where 48,790 fans should’ve been offered free Dramamine tablets.

Yankees ace Gerrit Cole didn’t have it, Aaron Judge (0-for-4, 3 Ks) went missing at the plate, but Royals manager Matt Quatraro was left to regret his decision to lift Michael Wacha in the fifth.

On the Yankees’ side, Aaron Boone made the right calls by starting Oswaldo Cabrera at first base and Alex Verdugo in left, with Verdugo delivering the final, go-ahead RBI single in the seventh.

"I understand it. I was booing myself, too,'' said Verdugo (2-for-3, walk), whose offensive numbers were under water all summer, inviting rookie Jasson Dominguez into the left field conversation.

Luke Weaver channels his inner Mariano Rivera

Jazz Chisholm Jr., a frequent flyer next to Weaver on team charters, had mentioned Weaver was “built for that moment,’’ entering Saturday with a runner at first base in the eighth.

Less than a month removed from his first big-league save - a moment in which he said he blacked out - Weaver, 31, retired the top of KC's order in the ninth.

Weaver got Michael Massey swinging at a changeup, caught Witt Jr. looking at a close, full-count, 96-mph fastball, and got Vinnie Pasquantino to ground out on a changeup.

“This is his time, this is what he’s made for,’’ said Chisholm Jr., who has seen that Weaver demeanor on the diamond, and when he’s holding diamonds.

Those in-flight card games can get ultra-competitive too, and “I’m a bad, visible shower of my losing,’’ said Weaver, though he was appreciative of Chisholm Jr.’s comments.

“Jazz had a lot of really nice things to say," said Weaver. “I wish he would say that to my face, our friendship would really take a leap.’’

A narrow Yankees' victory

Cole felt the Royals were "on top of their game against him,'' and that "I made my fair share of mistakes, that's for sure. Need to be sharper.

"But they put a couple really good pitches in play, too,'' including MJ Melendez's two-run homer in the fourth.

Kansas City can still get out of the Bronx with a split, with Cole Ragans opposing Carlos Rodon on Monday night - following a head-shaking off-day built into the AL playoff schedule.

But they might lament not stealing one against a not-at-his-best Cole, and that more-than-questionable send by third base coach Vance Wilson, getting Salvador Perez thrown out at the plate - the first out in the second inning.

Gleyber Torres (two-run homer, two walks) and Juan Soto (3-for-5, threw out Perez from right field) performed, Austin Wells - a .111 hitter in September - picked up Judge with a two-out, game-tying RBI single in the sixth.

And maybe Chisholm Jr. was out trying to steal second in the seventh, but the Yanks survived that replay challenge and Verdugo came through with the winning hit.

And the baseball for Weaver’s first career save is already in a box, with the date and score.

“It means a lot to me," Weaver said. “It’s everything you dream of, it’s definitely all the cliches rolled into one."

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