KANSAS CITY -- On Monday, Angel Zerpa turned 22 years old. On Wednesday, he found out he was being promoted to Kansas City to make his Major League debut.

A day later, the Royals’ No. 18 prospect turned in a stellar performance at Kauffman Stadium.

Zerpa limited Cleveland to three hits and allowed two unearned runs in the Royals’ 6-1 loss Thursday night, finishing the season series with their AL Central rivals. The only stain on Zerpa’s outing came in the third inning, when third baseman Adalberto Mondesi made a slick diving grab on a sharp ground ball but threw too low to first base, allowing Roberto Pérez to reach on a throwing error. He came around to score on Oscar Mercado’s one-out double -- the first hit Zerpa allowed.

The Royals offense left nine on base and couldn’t push a run across after the second inning, when Carlos Santana’s RBI single scored Andrew Benintendi. So Zerpa (0-1) was handed the loss despite having a 0.00 ERA in his very brief career.

"He was terrific," manager Mike Matheny said. "It looked like he’d been here for a while. That’s hard to do. But the stuff is going to play. … He looked advanced, especially when you take into consideration his age."

At 22 years, three days, Zerpa became the youngest pitcher to start for the Royals since Zack Greinke (21 years, 344 days) in 2005. Triple-A Storm Chasers manager Brian Poldberg told Zerpa on Wednesday that he was going to the big leagues, which the lefty admitted shocked him a little considering it’s the final week of the regular season and he had only made one start in Omaha after spending most of the season in High-A and Double-A.

"I felt really good," Zerpa said through interpreter Luis Perez. "I felt a little bit nervous in the bullpen, but when I [went] out to walk to the dugout, I didn’t feel [anything]. I was focused on throwing strikes, attacking the ball."

That’s exactly what Zerpa did, navigating his five strong innings on 68 pitches.

It’s easy to see why, when the Royals needed a fresh starter for Thursday’s game in order to give the bullpen a break, they turned to Zerpa. Logistically, it made sense; he was already on the 40-man roster, added last offseason to protect him from the Rule 5 Draft.

But the Royals wouldn’t have put him on the mound at The K if they didn’t think he was ready, and that belief was on display Thursday. He pounded the zone with his 94-95 mph fastball and mixed in his slider and changeup well to keep Cleveland off balance.

He also made it clear he wasn’t afraid to attack inside, getting quite a few called strikes there. Zerpa made his confidence of pitching inside known during Thursday’s pitchers’ meeting.

"That got everybody’s attention, like, ‘OK, now let’s go see it,'" Matheny said. "And he wasn’t just giving lip service. He was pounding the zone and pounding in and not afraid to [do it]."

"I don’t remember him throwing that hard like he was today, and his breaking ball was a lot sharper," catcher Cam Gallagher, who was also 2-for-4 Thursday, added. "His fastball was coming out of his hand really well. A lot of late swings, weak contact. He did a heck of a job."

What puts Zerpa, who signed out of Venezuela in 2016, on another level is his pitchability and composure. And that was apparent Thursday. In the fifth inning, Zerpa pitched around the right-handed-hitting Myles Straw in order to get to lefty Bradley Zimmer instead.

Straw didn’t bite, so Zerpa faced Zimmer with two on and two outs. The count ran full before Zerpa placed a 95-mph fastball on the outside part of the zone for a called third strike to end his outing on a high note.

"That was one we were encouraging from the side, for him to be able to put all that into play and try and get a chase and then go after the left-left matchup," Matheny said. "You just don’t see many young pitchers be able to think their way through that and then execute."

Thursday was Zerpa’s first and last start for Kansas City in 2021. But thoughts of what he could do in 2022 for this pitching staff were already making its way around by the end of the night.

"He handled himself a lot better than I did when I made my debut, I’ll say that," Gallagher said. "He was really composed. It did look like it was his 15th or 20th time doing it. … He did really well today, and there’s a lot to look forward to."