NEW YORK -- The Brewers have finalized their Opening Day roster -- and for the last player on the team, the call came out of nowhere.

Infielder Oliver Dunn, Milwaukee's No. 22 prospect, is the player who's taking the place of injured outfielder Garrett Mitchell, who fractured a bone in his left hand during batting practice less than a week before the season started. Dunn is one of 12 Brewers making their first Opening Day roster in 2024.

The 26-year-old was not expected to make the team out of Spring Training. Dunn was optioned to Triple-A last Tuesday and was preparing to start his season with Nashville.

But Mitchell's injury opened the door for Dunn -- who had a breakout season in the Minors last year, was great in the Arizona Fall League and then impressed the Brewers with a strong spring -- to get his first big league callup.

"At some point, I was expecting for it to happen; I was hoping for it to happen. But not on Opening Day," Dunn said. "Being told I was going somewhere else, and then all of a sudden last minute flipping to Opening Day in New York, it's awesome. Big stage, big moment."

Dunn will serve as a utility infielder with the big league club, part of a defensive realignment the Brewers will implement with Mitchell out.

Mitchell was in line to be Milwaukee's starting center fielder. Instead, Sal Frelick, who was going to be a regular option at third base after working there all spring, will go back to the outfield. Frelick will start in center field against right-handed pitchers, manager Pat Murphy said Wednesday. The switch-hitting Blake Perkins is expected to play center against lefties.

Frelick's move back to a primary outfielder means the Brewers need an extra infielder, preferably a lefty bat, who can take reps at third base along with Joey Ortiz and Andruw Monasterio. Dunn fits the bill.

"I had kind of shifted out of the Spring Training mode into Nashville mode," Dunn said. "But mindset-wise, that didn't shift a bunch. I'm still gonna play my game. I know that my role, whether I was here or there, it's probably two different roles. But the goal is still to win as many games as I can, and have as many productive ABs and productive innings on defense."

Now it's official, with the Brewers announcing their Opening Day roster on Thursday, the day before they open the 2024 season against the Mets at Citi Field. Thursday's scheduled Opening Day was postponed to Friday due to rain.

Dunn's solid production from the 2023 season into Spring Training 2024 put him in this position. Look at Dunn's numbers at each level he's played since the start of last year:

2023 Double-A:
119 G, .271/.396/.506, .902 OPS, 21 HR, 16 SB

2023 Arizona Fall League:
19 G, .343/.455/.616, 1.071 OPS, 2 HR, 12 SB

2024 Spring Training:
17 G, .282/.404/.487, .891 OPS, 1 HR, 5 SB

Dunn had just finished the drive to Nashville with his wife when he got the call from Murphy. The Brewers manager, of course, had some fun with his young prospect, grilling Dunn on why he'd left Spring Training without saying goodbye and wasn't keeping in better touch with the team.

"He just called me, and a call from Murph in the middle of the day was not expected, so I knew something was up," Dunn said.

Finally, Murphy broke the news by telling Dunn: "Look, if you're not gonna be one of us, we're gonna have to send you out ¡­ I think we're gonna send you to New York." That's when Dunn realized what was going on.

"I said, 'Yeah, you're going to be on the Opening Day roster,'" Murphy said.

So Dunn hopped on a flight to New York for his first Opening Day, and all of a sudden he has the chance to make his Major League debut.

"It was just a whirlwind of a day," Dunn said. "But it's the call everybody wants at some point."