ANAHEIM -- When it comes to debut outings, Jackson Kowar’s MLB debut was one that did not go as imagined.

Kowar, the Royals’ No. 4 prospect according to MLB Pipeline, began his night by getting Justin Upton out on a slow ground ball to first base, but struggled from then on in the Royals’ 8-3 loss to the Angels at Angel Stadium on Monday.

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“Very clear in our conversation that there's a lot going on in that first day out there,” Royals manager Mike Matheny said. “Even I told him on the mound [his] stuff looks good and that stuff's gonna be in this game a long time. Just take one of these days as those growing opportunities and just a stepping stone, because he's not going to have another like that. ... He's got too good of stuff and the way he competes.”

Kowar walked Shohei Ohtani, allowed a single to Anthony Rendon, walked Jared Walsh and gave up a single to Max Stassi before recording his second and final out of his first MLB outing.

After retiring José Iglesias on a groundout and allowing a single to Juan Lagares, Matheny made the walk from the dugout to remove Kowar and replace him with veteran Ervin Santana after just two-thirds of an inning.

“I would say that first hitter or two, [and] by the Ohtani at-bat, I was pretty juiced,” Kowar said. “After that, the heart rate came down a little bit and I just tried to make pitches and [it] just came down to me not really executing. Probably the first two hitters [there] was a lot of juice, but after that, it was just me not executing pitches. Not so much the adrenaline.”

The rookie showed off his sharp fastball that hovered around 95-96 mph and at times touched 97. His command, however, was sporadic. He threw 39 pitches (21 strikes), including three wild pitches, and couldn’t get any of his 16 changeups over the plate for a called strike. Only three of his pitches were called strikes.

With his family in attendance for the debut after letting them know about the callup on Saturday, Kowar said it was still memorable despite the result.

“I think when I hopefully look back and in the future, it's going to be a good story to tell,” he said. “Just happy they were able to come out.”

Hunter Dozier, who went 3-for-4 with two doubles and an RBI, saw Kowar perform while in Omaha during an injury rehab assignment.

Dozier said Kowar’s outing was just part of the nature of baseball.

“It's just part of it,” Dozier said. “I'm one of his biggest fans. I saw him in Triple-A when I was down there for my rehab assignment. When I came back, I was telling everyone, 'Hey, this kid is the real deal. He needs to be up here.' It's just one outing. He's got electric stuff. And he's going to be good for us for a long time.”

The highly touted prospect turned heads in the Minors before getting the call to the big leagues. He went 5-0 with Triple-A Omaha and led qualified Triple-A pitchers in ERA (0.85) and batting average allowed (.165) while ranking second in WHIP (0.88) through his first six starts.

Kowar was the 33rd overall pick in the 2018 MLB Draft by the Royals. In his Draft class, the Royals took four pitchers with their first four picks. All of them have already made their MLB debuts.

The other picks included Daniel Lynch (34th overall), Kris Bubic (40th overall) and Brady Singer, who was the 18th overall pick and a teammate of Kowar’s at University of Florida, where the two were roommates and 2017 College World Series champions.

After Kowar got back into the dugout following his early exit, Kowar said Singer was able to provide a different frame of mind for his former college teammate.

“[He was] just trying to give me some perspective on everything,” Kowar said. “Just being a good teammate. Other than that just kind of taking my mind off it probably. He could tell I was obviously frustrated.”