KANSAS CITY -- The Royals were one out away from another gritty comeback win on Tuesday night, one centered around the way the offense rallied for another big inning and the pitching coming through once again.

Then, Brewers catcher William Contreras won an eight-pitch battle with Royals closer James McArthur, sneaking a ball just fair down the third-base line for a double.

McArthur followed that by walking Gary Sánchez with four pitches not close to the zone.

Willy Adames delivered the final blow with a three-run home run, giving the Royals a gut-punch 6-5 loss and McArthur’s second blown save in three days at Kauffman Stadium.

“Really frustrating,” McArthur said. “Supposed to be a curveball down, hung it up in the zone a little bit. [Adames is] a guy where you can’t make that mistake, especially late in the game. He made me pay, made us pay. Really frustrating.

“Didn’t want to throw that pitch there. Bad result.”

The Royals had McArthur on for the ninth because the offense rallied with a four-run fifth inning. The pitching was elite again late, when reliever John Schreiber worked around two hits for a scoreless eighth inning.

“Couldn’t be more proud of the way they battled and then expanded later on,” manager Matt Quatraro said. “We’ll take our chances with Schreiber and McArthur every day.”

McArthur won the closer job last September when he ended the season with a 16 1/3-inning scoreless streak and again early this season even after the Royals retooled their bullpen to bring in experienced high-leverage relievers.

Entering Tuesday, McArthur had a 2.87 ERA this season with seven saves, and a 1.41 ERA with 11 saves since his recall last Sept. 1.

The Royals have gone to him enough in the ninth inning that the organization began recently using a closer’s entrance for him at The K, having the lights flicker while Chris Stapleton’s “White Horse” blares through the PA system.

But in his past two games (three innings), McArthur has allowed five runs (four earned) and picked up his first two career losses.

The message to McArthur?

“He’s going to keep getting opportunities to pitch in high leverage,” Quatraro said. “We’re not backing away from it. He’s good. Sometimes you get beat.”

McArthur’s stuff and steady presence gives him high upside in those big spots. The Royals have been clear in their confidence in him, even when they looked for ways to upgrade their bullpen this offseason and into Spring Training.

But the 27-year-old with 40 career innings under his belt is still learning on the job. No one is perfect, and McArthur is learning how to bounce back from tough nights.

As crushing as Tuesday’s loss was, McArthur simply has to look around the Royals’ clubhouse for examples on how to get through it. Experienced relievers like Will Smith and Chris Stratton are in the corner across from McArthur available for advice.

Across the room stood Seth Lugo, who has plenty of bullpen experience from his time with the Mets. Lugo, who allowed three runs in 6 2/3 innings against the Brewers for his seventh quality start of the year, knows how McArthur feels -- and how he can bounce back from it.

“I know what it’s like to have a rough outing or two out of the ‘pen,” Lugo said. “To be able to flush that and move forward, it’s something you learn how to do as you get older. Lot of the time, it’s not necessarily very easy to do alone.

“As a team, we’re going to have his back, and we’re going to pull for him and hope that [he] and [we] can get it together, and turn the page.”

The hitters, too, expressed their confidence in McArthur.

“If James thinks that anybody has lost confidence in him, he’s in the wrong locker room,” said Vinnie Pasquantino, who logged three hits and three RBIs. “Who cares about what’s happened the past two nights for him? Who cares? I know when he goes out there, we’re going to win the game. Didn’t happen tonight. Didn’t happen the other day.

“I grounded into two double plays last night, was pretty much the Brewers’ best player, and we still won the game. The guys had my back last night. James has nothing to worry about.

“He’s going to wear it tonight. That’s fine. That’s what competitors do. … He should know, and if he doesn’t, I’m going to go tell him right after this, that nobody cares what happened tonight. We’re upset. We’re disappointed with the loss. But we gotta get back at it tomorrow and win a series. That’s our job.”