MILWAUKEE -- First home run milestones will always be one of the greatest accomplishments in baseball. It’s a sign that a player’s hard work has paid dividends and all the countless hours they spent training were worth it. They’re now playing at the highest level in baseball: It’s a dream come true.

On Monday night, Diego Castillo got to live out his dream by belting his first career home run in the fourth inning of the Pirates’ 6-1 loss to the Brewers at American Family Field.

“I dreamed about this moment,” said Castillo. “I’m proud that I got my first home run in the big leagues. I’m gonna add it to the best moment of my life list.”

The 24-year-old will always remember his first career home run not only because of the milestone but also because of the strange sequence prior to it. On a 1-1 count, the rookie swung on a pitch that hit him in the right knee. After limping around for several seconds, he was ready to go.

“It hurt a little bit in my knee,” said Castillo. “But I still had one more strike, and then in my mind, I said, ‘Hit the ball and run the basics, let’s see what happens.’”

With that approach, Castillo got back into the batter's box, then on the next pitch he launched a 360-foot home run.

In his first at-bat against Brewers pitcher Eric Lauer, Castillo battled the lefty for eight pitches, fouling off four consecutive pitches before striking out. But in his second at-bat, he remained composed and waited for his pitch, a 94 mph fastball up in the zone.

“He continues to play well,” said Pirates manager Derek Shelton. “[He] continues to have good at-bats.”

That prestigious home run ball that Castillo drove to right field won’t be in his possession very long, as he plans on giving it to his mom to keep.

“Every time when I was in Little League, she was always with me,” said Castillo. “She always dreamed about having a son in the big leagues. Everything that I do here in the big leagues is gonna be sent to my mom.”

Castillo’s home run adds to an already impressive rookie campaign. The homer was his eighth hit in the past seven games, and it was his third consecutive game with an RBI.

“He’s a baseball player,” said Shelton. “Any place we put him, anything we’ve done with him, he’s responded to it. He just continues to get better. And that’s important. I mean, getting better at the Major League level is a challenge and he’s done that so far in the first 10 games.”

The power that Castillo showcased in his first career home run hasn’t always been there. From 2015-19, as a part of the Yankees' Minor League system, the Venezuelan-born infielder struggled to show any type of power. He homered just eight times in five years.

But in 2021, Castillo homered 19 times, more than doubling his home run total from the previous five. He credits his confidence for taking the new step in his game.

“When you have that confidence, good things are gonna happen,” Castillo said.

That same confidence was carried with Castillo throughout Spring Training. His six home runs and 12 RBIs led the Pirates, and he finished with a .371 average to lead all players who made the Bucs' Opening Day roster.

Those question marks about Castillo’s power have slowly started to fade and he is exceeding Pittsburgh’s expectations so far.

After going 2-for-4, Castillo brought his batting average up to .310. His nine hits are tied for third on the team behind Ke’Bryan Hayes and Bryan Reynolds.

It’s a feel-good story for Castillo, who was battling for a spot on the Opening Day roster. Now, he’s making a case to be the everyday second baseman for the Bucs.

That home run will be a moment that the young rookie will never forget.

“First place, 100 percent,” said Castillo when asked where this moment ranks.