JUPITER, Fla. -- Right-hander Miles Mikolas is encouraged after receiving a platelet-rich-plasma injection on Tuesday for his sore right forearm, an injury that will keep him off the Opening Day roster.

Mikolas, now in the second year of a four-year, $68 million extension, was the Cardinals’ Opening Day starter last season.

"If I'm a couple weeks late to the season, I think that'll be the end of it," Mikolas said on Thursday. "I'll be back just like normal."

The 31-year-old Mikolas will be shut down from throwing for at least a week, "but after that, it just depends on how I feel, how much I can do as far as the exercise and the rehab schedule," he said.

Mikolas had received a PRP injection in late October for a similar issue with his flexor tendons, which connect the muscles of the forearm to the bones in the fingers and thumb. He felt discomfort again during his first bullpen session last Thursday.

Mikolas said the second injection zeroed in on where most of that inflammation was, and that an MRI and ultrasound showed that his ligament is in "great shape."

Though Mikolas can't throw for now, he'll be alongside his teammates at the Roger Dean Chevrolet Stadium complex until the Cardinals break camp for the season. Where he continues his rehab when the club leaves for Cincinnati for Opening Day on March 26 has yet to be decided.

Thursday was another rest day, because Mikolas' arm is still tight from the fluid in it. He expects to return to running on Friday and Saturday, and to the gym on Sunday and Monday to keep his strength up. Pitchers' fielding-practice drills start sometime next week.

"It depends on how quickly I can get ramped back up," he said. "I was already throwing bullpens, so it's not a 'start from scratch' kind of thing. It all just depends on how quickly I can get ramped up and what the team needs when I'm ready."

Added manager Mike Shildt: "[I told him], 'Stay with the camp, progress with this mentally, progress with as much as you can physically and just stay engaged.' I've had that conversation with him, but I'm really just telling him things he already knows. My conversation is more, 'How are you feeling? How did it go? How are you recovering? What's it feel like?' Making sure we stay in touch with a plan."

With Mikolas sidelined, the Cardinals have Carlos Martínez, Kwang-Hyun Kim, John Gant, Ryan Helsley, Génesis Cabrera, Daniel Ponce de Leon and Austin Gomber as options to fill out the rotation.

Additional pitchers announced for Saturday

Right-hander Dakota Hudson, as well as left-handers Brett Cecil and Kim, will follow Jack Flaherty in the Cardinals' Grapefruit League opener against the split-squad Mets. First pitch is scheduled for 12:05 p.m. CT at Roger Dean Chevrolet Stadium.

Shildt said that Kim, whom the Cards signed to a two-year deal this offseason, might go just one inning in his debut.

"It just sets him up," Shildt said. "We've got innings. Get him out there an inning and then go from there. He's obviously still being used as a starter. It's his first game."

Kim could be used either in the rotation or bullpen. He went 17-6 with a 2.51 ERA in 31 games (30 starts) last season in the Korean Baseball Organization.

"I think what we've learned is that if you've got starter stuff, you can have reliever stuff," Shildt said. "I think his stuff plays either way."

Waino's debut

When asked who would pitch on Sunday against the Marlins, Shildt replied, "We do have something in mind. I'd say [Adam] Wainwright would be a good possibility."

The 38-year-old right-hander, who threw a bullpen on Thursday, didn't know if 2019 -- his 14th MLB season -- would be his last. He wound up signing a one-year deal with the Cards as a first-time free agent.