News of Miles Mikolas’ availability for Opening Day -- or, rather, his lack thereof -- made official what the Cardinals feared through the first few weeks of camp: There are now two spots in the rotation to fill.

It remains to be seen how long the soreness in Mikolas’ right shoulder will keep him out -- the club hopes it’s just a slightly longer-than-normal, non-invasive recovery -- but with the No. 5 spot already open and Mikolas initially penciled in at the No. 3 or 4 slot, the Cards will need two arms to step up by April 1.

The rotation as of March 10:

1. Jack Flaherty
2. Adam Wainwright
3. Kwang Hyun Kim
4. TBD
5. TBD

And the candidates (listed in order of their likelihood of winning a spot):

1. Carlos Martínez
2. John Gant
3. Daniel Ponce de Leon
4. Jake Woodford
5. Johan Oviedo
6. Zack Thompson

Notably not listed among the candidates is Alex Reyes, the uber-talented 26-year-old righty. Citing durability concerns and long-term vision, the Cardinals on Tuesday said that Reyes will be a bullpen arm in 2021, limited to 100 innings, though he could make some cameos in the rotation as the season progresses.

The Cardinals were tied to several starting pitchers in the free-agent rumor mill, but none of those has come to fruition. The club has expressed confidence in its pitching depth this spring, more so than in years past. That’ll be put to the test as the club attempts to fill out its crop of starters for Opening Day in Cincinnati.

Barring any moves, here’s a look at the candidates who could fill out the rotation behind Kim at the start of the season.

Carlos Martínez, RHP
The story: Feeling refreshed and ready to go
The outlook: As close to a surefire favorite as can be

Martínez struggled mightily in his first Grapefruit League outing but rebounded for a crisp trio of innings on Tuesday, becoming just the second Cards starter to make it out of the first inning this spring. After pitching in winter ball, helping lead his club to the Caribbean Series championship, Martínez feels fresher this spring -- physically, in terms of the innings already under his belt, and mentally, in terms of his focus after a tumultuous, injury-riddled 2020 season.

John Gant, RHP
The story: John Gant: Good at baseball?
The outlook: Inside track for the No. 5 spot

A magnet to trending on Twitter, Gant has seen his chances for the rotation increase with Mikolas’ setback. He wants to start, and the club is giving him every chance, with a three-inning workload last time out. Though Gant hasn’t made a start since 2018, his track record is positive, as he's compiled a 3.43 ERA in 81 games as a reliever since.

Daniel Ponce de Leon, RHP
The story: Stuff has played as a starter
The outlook: Nipping at Gant’s heels for fifth spot

Ponce de Leon may fall victim to the numbers, as Martínez and Gant likely hold the keys to the final spots in the rotation, but he’s done nothing to fall out of the conversation, striking out six over his first four innings this spring. He’d be a prime candidate if the Cardinals decide they want to work in a sixth starter, or if they employ the piggyback pitching method, which they have been open to considering.

Jake Woodford, RHP
The story: Former prospect looking for a fit
The outlook: Swingman with spot starts possible

The Cardinals think very highly of Woodford, one of their two first-round picks in the 2016 MLB Draft. He hasn’t found sustained success in professional ball yet, but after getting his first taste of the big leagues last season, he’s a prime candidate to be a swingman, coming on in long relief or making spot starts. If not, he’ll be one of the first names called up from Triple-A Memphis.

Johan Oviedo, RHP
The story: High ceiling, opportunities few
The outlook: Fringe rotation arm likely destined for bullpen

Few players have received as much unprompted praise this camp as Oviedo has. The only catch: his build-up. Oviedo was scheduled to make his Grapefruit League debut on Wednesday, and it comes with just three weeks to go until Opening Day and the starters in their third turn through the order. His usage, at least at the outset, is likely to come in the bullpen as a multi-inning arm.

Zack Thompson, LHP
The story: Club’s No. 5 prospect giving off good vibes
The outlook: Soon, young Padawan

Thompson has been able to offer a brief glimpse at big league camp, making one appearance against the Nationals. But it was a positive one, providing a peek at what he can provide to a rotation … likely later in the season, if at all before 2022.