LOS ANGELES -- Junior Fernandez thought he was hearing a joke.

But Triple-A Memphis manager Ben Johnson was not messing with him.

“He asked me how far away I was from the field,” Fernandez said. “So I was like, ‘Uh, five minutes?’ And he said, ‘OK, go get your stuff because you’re going to the big leagues tomorrow.’ I couldn’t believe it. I thought he was joking. He said, ‘I was not going to call you to tell you a joke.’”

The rookie right-hander made it to Dodger Stadium on Tuesday afternoon after the Cardinals purchased his contract from Memphis. In a corresponding move, the Cardinals designated for assignment left-hander Adalberto Mejía. Mejia was claimed off waivers July 30 and appeared in two games for the Cardinals, giving up eight hits and three runs in three innings.

Fernandez, 22, is the club’s No. 10 prospect, according to MLB Pipeline. He signed in 2014 as an international free agent out of the Dominican Republic, was moved to the bullpen last year after arm trouble and has soared through the Minor League system this year with a dominant fastball and a plus changeup.

In 42 games between Class A Advanced Palm Beach, Double-A Springfield and Triple-A Memphis, Fernandez had a 1.47 ERA. He struck out 23 batters in 20 2/3 innings since making his debut with Memphis on June 25.

“I wasn’t really surprised [how fast I moved through the system] because I felt like I was pitching pretty good,” Fernandez said. “My teammates kept telling me, ‘Hey, keep doing this; you won’t be here long.’ It was just go out there and show it every time. And now I’m here.”

The Cardinals have been excited about Fernandez since moving him to the bullpen at the beginning of the 2018 season. Even Yadier Molina -- who was in Memphis on Monday for his rehab assignment -- made it a point to mention the pitcher when talking to Cardinals manager Mike Shildt.

“He was like, ‘I caught Fernandez, he has really good stuff, we need him,’” Shildt said. “And I was like, ‘He’s coming.’”

Shildt said Fernandez might not be available Tuesday night after throwing back-to-back nights in Memphis, but Fernandez is built up to go multiple innings, even though he was mostly used as a high-leverage pitcher in Triple-A.

“Like most guys, they earn their way to the big leagues,” Shildt said. “They tell you, ‘Hello, I’m down here.’ He’s done that. Once we started to recognize that, have communication with our player development group that he’s coming and getting closer, we talked to everybody about getting him some more multiple-inning looks. So he’s now built up, based on his pitch count and innings. He’s not a one-inning guy. He’s actually thrown up to 35 pitches.”

The move comes after starter Michael Wacha made it just 3 2/3 innings Monday in an 8-0 loss to the Dodgers. Mejia then pitched 1 1/3 innings, and Ryan Helsley threw 60 pitches in three scoreless innings.

The Cardinals also announced that right-hander Mike Mayers cleared waivers and was assigned outright to Memphis. Mayers was designated for assignment Sunday and will try to work his way back to the Cardinals’ bullpen.

When a player's contract is designated for assignment -- often abbreviated "DFA" -- that player is immediately removed from his club's 40-man roster and 25-man roster, if he was on that. Within seven days of the transaction, the player must either be released or placed on irrevocable outright waivers.

Players’ Weekend nicknames announced

Tommy Edman wanted to channel his inner Michael Scott with his original Players’ Weekend nickname, Agent Scarn, from the “Threat Level Midnight” episode of “The Office.”

Although the nickname was nixed because of copyright issues, Edman -- who went with “Eddie” as his nickname instead -- said it’ll still be on his mind when the Cardinals take the field during Players’ Weekend from Aug. 23-25.

• Every team's Players' Weekend nicknames

“That’s my PlayStation gamer tag, Agent Scarn, but they wouldn’t let me,” Edman said. “I was kind of bummed. “The Office” is my favorite show. I don’t know how many times I’ve watched it through because it’s been so much. But I’m still excited.”

During Players’ Weekend, players will showcase their passions, backgrounds and interests by putting their own personal touches on what they wear and equipment they use. Players are given the chance to design, wear and use creatively colored and decorated equipment, including bats, spikes, batting gloves, wristbands, compression sleeves and catcher’s equipment.

Worth noting

Molina (right thumb tendon strain) will continue his rehab in Springfield on Thursday after he homered on Monday with Memphis. Molina was back in St. Louis on Tuesday for a checkup, and Shildt said the report was positive.