WEST PALM BEACH, Fla. -- On his first day after becoming a rostered MLB player for the first time, 20-year-old Cardinals phenom Jordan Walker had to choose between a couple of difficult tasks. He could either work on answering some of the approximately 750 text messages on his phone, or he could pick a new jersey number he would showcase at Busch Stadium for Opening Day.

“I [am] not a great texter,“ admitted Walker, giving a glimpse at which task he chose to undertake first.

Walker, baseball’s No. 4-ranked prospect, per MLB Pipeline, learned Saturday afternoon that he had made the Cardinals' 26-man Opening Day roster following a heartfelt meeting with manager Oliver Marmol and bench coach Joe McEwing. Marmol praised the 6-foot-5 converted outfielder for showing up to Spring Training ready to compete, taking the Grapefruit League by storm with an early power surge and not shrinking when he struggled of late.

Like what legendary Cardinals slugger Albert Pujols did in 2001 when he made the big league club while playing only minimally at Triple-A, Walker jumped to the bigs straight from Double-A. Also, like Pujols, Walker will likely start in left field on Opening Day, and he’ll try and notch his first hit as Pujols did 22 years earlier.

Walker will enter his first MLB season while wearing No. 18, his old number from his travel-ball days as he was making a meteoric rise through baseball’s ranks. He wore No. 22 in Double-A as a nod to his birthday: May 22, 2002, at 2:02 p.m. in Room 202. However, that number is already worn by Cardinals right-hander Jack Flaherty, who struggled with six earned runs on four hits and three walks allowed in a 24-1 loss to the Astros on Sunday at The Ballpark of The Palm Beaches.

The No. 67 that Walker wore in Spring Training while smashing home runs of 470, 450 and 430 feet and five doubles will serve as an answer to a trivia question someday. Now, it’s a new day and time for a new number.

“I wore 18 in travel ball a lot when I was younger,” said Walker, who doesn’t turn 21 until May 22, will be the youngest Cardinal to make his MLB debut since Rick Ankiel (age 20.035) on Aug. 23, 1999, and the youngest position player to debut since David Green (age 20.274) on Sept. 4, 1981. “I wore 22 last year, and honestly, I don’t care about my number. … When I saw 18, it just kind of called out to me. I wore it before, and it seemed to be an epiphany for me.”

Marmol is more concerned with the numbers Walker can put up for the Cardinals than the number on the rookie’s jersey. Already, he has stressed to Walker about the need to keep working at the big league level so that he can maximize his seemingly limitless potential.

“He's going to get better at a lot of things,” Marmol said of Walker, who will wear No. 18 just as famous Cardinals Mike Shannon, Keith Hernandez and Andy Van Slyke did before him. “To me, things go hand in hand with him. You’ve got work to do, and you’re really good, but neither of us know what your ceiling is. I have no idea what's possible for [Walker], and we have no idea what's possible.

“What we do know is how to go about our work and find out what's possible,” Marmol added. “I can [not] care less about Opening Day because we're playing 162 [games]. You can punch out four times, and I don't care about Opening Day. You're going to be nervous; figure it out, and let's continue to get better. I don't place as much emphasis on Opening Day as much as what's possible and how do we get there?”

When Walker gets to Opening Day, it will be his first time at Busch Stadium for a game. Because he was drafted in 2020 during the COVID shutdown, he couldn’t travel to St. Louis to watch games. Now, his MLB debut will come before National Baseball Hall of Famers Ozzie Smith, Whitey Herzog, Ted Simmons and Scott Rolen -- and the Budweiser Clydesdales and a raucous, sellout crowd.

As special as that moment promises to be, it likely won’t top the chills he felt after being informed his MLB dreams were becoming reality.

“It was unbelievable joy,” he said. “I don't think I've ever had a feeling like it. One of the best feelings in my life, for sure.

“For me, as a kid growing up and wanting to be in MLB, I felt at some point I would get to this moment, and it was everything I thought it would be,” he added. “The feelings were high, and my happiness was high.”