MESA, Ariz. -- There is a sign off Tennessee State Route 111 welcoming visitors when they enter the town of Sparta. Inlaid in the large stone is a tribute to bluegrass legend and local hero Lester Flatt.

When Cubs pitcher Ethan Roberts was 12 years old, he drove by that sign with his father and made a bold prediction.

"I said, 'Dad, that's going to say, "Home of Ethan Roberts," one day,'" the rookie pitcher said. "I've been thinking about this for a long time."

An important step in that dream has arrived for Roberts. In the midst of the Cubs' 15-9 Cactus League win over the White Sox on Monday, Cubs manager David Ross informed the rookie right-hander that he made the Opening Day bullpen.

Upon hearing the news, Roberts sunk back on the bench, leaning against the wall with a stunned smile on his face. He received a hug from pitching coach Tommy Hottovy and put his head in his hands. Emotions overwhelmed the young pitcher.

"I just melted," Roberts said. "This is life-changing for me. This is insane. I'm just at a loss for words. Yeah, it's hard to put it into words. I don't know what to say, but it's just something I've been dreaming about for a long time."

The 24-year-old Roberts received that news after working the fourth inning against the White Sox. The last batter of the frame, slugger Jos¨¦ Abreu, sent a sharp comebacker up the middle, striking Roberts' right hand before the pitcher retrieved the ball and recorded an out.

When Roberts reached the dugout, Ross had a question for him.

"Rossy comes up and he's like, 'Hey, can you still shake my hand?'" Roberts said. "I was like, 'Yeah, I'm good. My hand's fine. I promise. It's good.' He's like, 'Good, you just made the team.'"

This spring, Roberts impressed Ross with his maturity, poise and powerful repertoire, which the manager recently called "back-end stuff." Over five Cactus League outings, the hard-throwing righty racked up seven strikeouts with one walk in 5 1/3 innings, allowing zero runs.

"He's been really good, hasn't he?" Ross said prior to Monday's game. "His numbers have spoken for themselves. I think the way he's come out, the velocity has just continued to stay at a high level, the slider, the wipeout, the strikeouts, throwing strikes, all those things are really positive from a young guy."

Roberts¡¯ spring showing came after the Cubs opted to add the righty -- ranked No. 30 on MLB Pipeline's Top 30 Cubs prospects list -- to their 40-man roster. Last year, the righty had a 3.00 ERA with 72 strikeouts against 17 walks in 54 innings between Double-A Tennessee and Triple-A Iowa.

At the start of Spring Training, Roberts compared being rostered to the feeling of being drafted in the fourth round by Chicago in 2018.

What did this moment feel like to Roberts?

"This is like three different flavors of icing on top of that cake right now," he said with a laugh.

After being told he made the Major League bullpen, Roberts went back to the Cubs' complex and immediately called his wife, Hopelyn. At first, she asked if he was injured. When Roberts said that was not why he was calling, she figured it out.

"She goes, 'So, it's the other thing,¡¯" Roberts said. "And she's like, 'I've got to pull over.'"

Maybe someday down the road, visitors to Sparta, Tenn., will be pulling over to see that "Home of Ethan Roberts" sign. Lefty Stewart (1921-35) and Tom Rogers (1917-21) are the only Major Leaguers listed as being born in the small town.

Roberts will become the third with his next pitching appearance.

"It's just going to be¡­ ," he said. "I can't imagine what it's going to be like."