Looking to fill a void in their starting rotation, the Mariners will call up top pitching prospect George Kirby, the team announced on Saturday. He’ll be making his Major League debut today vs. the Rays.

“As the spring went along, he really improved. He got more comfortable,” Seattle manager Scott Servais said. “I talked to him today for a few minutes. 'You’re going to be nervous tomorrow. Just expect it’s going to happen. You know, how you deal with it, how you work through it -- ultimately you’ve just got to trust your ability.'”

Kirby’s promotion comes after the Mariners optioned No. 6 prospect Matt Brash to Triple-A Tacoma on Thursday, opening a spot in the rotation. Speculation about Kirby joining the big league club gradually built over the last two days and intensified after the righty was scratched from his start for Double-A Arkansas on Saturday.

With the Mariners planning to convert Brash to a relief role, Kirby, the team's No. 3 prospect and No. 30 overall according to MLB Pipeline, has a chance to make the spot his own.

“I told him today I’m not looking for eight innings out of him tomorrow,” Servais said. “Keep us in the ballgame, even if it goes a little rough early on. Keep filling up the strike zone. Take your chances.”

So far this year, Kirby has been sensational in the Double-A Texas League, going 2-0 with a 1.82 ERA and 32 strikeouts in 24 2/3 innings. The 24-year-old is coming off a 2021 campaign in which he logged a 2.53 ERA over 67 2/3 innings between High-A Everett and Double-A Arkansas.

Kirby has gradually picked up velocity since the Mariners selected him with the 20th overall pick in the 2019 MLB Draft out of Elon. He can now run his fastball up to 100 mph, turning what was a low-90s heater into one that sits in the 96-98 mph range consistently.