TORONTO -- The Royals’ youth movement has arrived.

Following Wednesday’s announcement that 10 players were unable to make the trip to Toronto because they are unvaccinated, the Royals called up eight replacement players Thursday afternoon: Infielders Nick Pratto, Maikel Garcia and Michael Massey; catchers Sebastian Rivero and Freddy Fermin; outfielder Brewer Hicklen; utility man Nate Eaton; and lefty Angel Zerpa, who got the start in the opener of the four-game series.

“It’s a tough scenario, it’s a tough situation,” Royals manager Mike Matheny said. “It has been from the very beginning. There are some very capable people who’ve made decisions and continue to make decisions for states and countries. We just abide by the rules that are given to us. The rules that we have now have left some of our players back, and we’ve got new players their opportunities.

“It’s different, it’s not how we’d design it, but it is where we are and now we move forward.”

The Royals’ starting lineup on Thursday featured seven players 26 years old and younger. Their starter, Zerpa, is 22 years old. Pratto, Garcia, Massey, Fermin and Eaton will all be making their MLB debuts when they appear in a game this weekend.

Bobby Witt Jr., the Royals’ rookie shortstop, has more plate appearances (352) than all but three players on Kansas City's active roster: Nicky Lopez (1,446), Ryan O’Hearn (997) and Zack Greinke (600).

“The message is that every single one of them deserves to be here,” Matheny said of the Royals’ callups. “They were right on the doorstep. We’ve talked about them, we’ve been watching them all season long. Don’t let the unique nature of it take away all they’ve done to make this a reality.”

The Royals still have two players they can add to the roster, because two of the 10 unvaccinated players are starters in Brad Keller and Brady Singer. Per MLB policy, pitchers who go four innings or more in their last start cannot be replaced until four days after that start, preventing teams from using that spot for an extra reliever. If Keller and Singer were on the active roster, they would be unavailable on the days they don’t start anyway.

Keller, who started Monday, can be replaced on Friday. Singer, who started Wednesday, can be replaced on Sunday. The Royals do have a taxi squad in Toronto, including left-hander Gabe Speier, right-handers Carlos Hernández and Collin Snider, infielder Clay Dungan and catcher Tyler Cropley.

The Royals also had three staff members who could not make the trip: Pitching coach Cal Eldred, assistant hitting coach Keoni De Renne and strategist/bullpen coach Parker Morin. Triple-A manager Scott Thorman is in Toronto to assist Matheny’s staff this series.

Here is what to know about each replacement player on the Royals’ roster -- several of whom are viewed as key parts of Kansas City’s future:

C Sebastian Rivero
After making his big league debut in 2021, Rivero has been a valuable depth piece for the Royals the past two seasons. The 23-year-old is a glove-first catcher, garnering rave reviews about his defense. He has a .710 OPS across 33 games with Double-A Northwest Arkansas this year.

C Freddy Fermin
The 27-year-old has served on the Royals’ taxi squad this year but hasn’t been activated to make his debut yet. That will change this weekend. Like Rivero, Fermin is lauded for his defense and has experience catching Kansas City's pitching staff. He has a .779 OPS across 40 games with Triple-A Omaha this year.

1B Nick Pratto
Ranked No. 69 on MLB Pipeline’s Top 100 list, Pratto boasts Gold Glove defense at first and a slugger’s mindset at the plate. The 23-year-old has mashed 17 home runs with Triple-A Omaha this year, and the Royals have experimented with him playing the corner outfield to increase his versatility, preparing for longer stints in the Majors this year.

2B Michael Massey
Massey, 24, jumped onto radars with a healthy 2021 and has shown no signs of stopping in ‘22. He won the MiLB Gold Glove at second base last year and is slashing .317/.373/.535 with 15 homers and 23 doubles between Double-A and Triple-A this year.

SS Maikel Garcia
Just 22 years old, Garcia is an elite defender, which is why he was added to the Royals’ 40-man roster over the offseason to be protected from the Rule 5 Draft. His bat is flashing contact tools this year as well, as he is hitting .287 with a .365 on-base percentage in Double-A.

INF/OF Nate Eaton
Perhaps the Royals’ most underrated prospect in terms of name recognition, Eaton is far from underrated on the field. A reliable defender, the 25-year-old is one of the more versatile players in the organization, playing all three outfield spots and all over the infield. He has unlocked more power than ever before this year, slugging .498 with 13 home runs in Double-A and Triple-A.

OF Brewer Hicklen
Hicklen made his debut earlier this year when Kyle Isbel was on the COVID-19 IL. The 26-year-old plays excellent outfield defense and has an .869 OPS in Triple-A this year.

LHP Angel Zerpa
The starter for Thursday’s series opener, Zerpa pitched two scoreless innings for the Royals on Monday. The 22-year-old lefty has a 4.36 ERA in Double-A this season.