Hunter Greene’s Reds debut on Sunday will mark his formal introduction as a Major League pitcher, but to pinpoint the first time he was initially noticed inside the game, you’d have to go back 15 years.

Throughout his childhood, Greene was a regular presence at many of Major League Baseball’s signature diversity-focused events and youth programs. His development was accelerated by having access to the state-of-the-art MLB Youth Academy in Compton, Calif., the first of 10 academies MLB has helped build across the country.

Greene’s journey to becoming a professional pitcher began in 2007, when he first stepped into the Compton Youth Academy as a 7-year-old.

Coaches, noticing Greene’s advanced athletic gifts, were tempted to push him a bit, and allow him to work out with a group of kids two years older than him. Eventually, however, they decided to keep Greene with his age group, and from there the youngster took off, both athletically and academically.

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Through the years, Greene, the Reds' No. 1 prospect, soared through several of MLB’s showcase youth events. In 2013, at age 14, he played in the RBI World Series. In '15, he participated in the Elite Development Invitational (now the Hank Aaron Invitational) and the next year, he was part of the High School Home Run Derby.

In 2017, the year Greene turned 18, he played in the DREAM Series, a showcase event focusing on the dynamics of pitching and catching for a diverse group of high school elite athletes, predominantly African-American, during the Martin Luther King Jr. holiday weekend.

Greene played in a host of other tournaments, including all-star games that pitted his teams against others from Australia and Japan. As a Compton Academy Junior Olympian, Greene traveled to Arizona to compete against top 13- and 14-year-old talent in the country. He was almost always the youngest player on the roster.

“For me, opportunities that were given to me at such a young age, like the Urban Youth Academy, the Elite Development Invitational, the Dream Series ... just being around the people and the event meant a lot to me,” Greene said during an interview with MLB Network in 2017. “It’s all about the opportunities. I really think that the people here, the players that are here can get that opportunity, that exposure, it’s definitely going to change their lives. Not just on the field as a baseball player, but as a person.”

Greene excelled academically, too. In 2013, his essay was picked as the winner of the prestigious “Breaking Barriers: In Sports, In Life” contest, developed in 1997 by Sharon Robinson, Jackie Robinson’s daughter.

Through the program, students were invited yearly to write about barriers or obstacles they faced in their lives and how they used the values exemplified by Jackie Robinson to deal with those obstacles.

Greene, whose family at that time was coping with his sister’s leukemia diagnosis and treatment, wrote about struggling to stay focused during such uncertainty.

“The value of persistence was very important in this situation,” Greene wrote in his essay. “It got me through my struggles with my sister [Libriti], who I love very much, while I was perfectly fine and out playing baseball.

“To me, persistence means finding a way to work through and stay focused during a tough situation, never giving up. My family helped me stay persistent with my athletic and academic goals, when in reality, we were not sure what was going to happen. I thought I was going to have to give everything up.”

Nine years later, Libriti is a thriving teenager, and her brother is on the cusp of the biggest moment of his career. Greene’s Major League journey officially begins on Sunday, but for many in baseball who have known him since he was barely 7 years old, watching him debut for the Reds will be like saying hello to an old friend.