SARASOTA, Fla. -- The Orioles’ Opening Day roster is unofficially set. They’ll open the 2019 season with their ace on the shelf.

The club placed Opening Day starter Alex Cobb on the 10-day injured list after wrapping up Grapefruit League play with a 9-7 loss to the Mets on Monday, a decision that all but solidifies its roster three days before the opener Thursday in New York. Right-hander Andrew Cashner will take the hill in place of Cobb, who suffered a mild right groin strain in his final Spring Training start.

“It stinks, it’s just awful timing,” Orioles manager Brandon Hyde said. “I know it was something he was really looking forward to, had a lot of people going. We were holding out hope that he’d be able to do it, but it just doesn’t seem like the right thing to do.”

Cobb’s IL stint is backdated to Monday, meaning he’d be eligible to return for the O's home opener on April 4. That’s the team's hope, with executive vice president and general manager Mike Elias citing “an abundance of caution” when further characterizing Cobb’s situation on Monday. The injury was considered mild enough not to require an MRI when Cobb initially felt discomfort on Saturday, and he then tested it with a game of catch Monday. He is expected to throw a side session Tuesday in Sarasota before joining the team in the Bronx as it opens the season against the Yankees.

"He thinks that was just a very minor flare-up of the groin," Elias said. "But for us we want to guard against the scenario where we march him out for Opening Day in the cold in New York, and then it’s re-aggravated and then now we’ve got to get somebody up out of the bullpen and scramble to figure out the rest of the rotation.”

Cobb joins catcher Austin Wynns, on the 10-day IL with a left oblique strain, and Mark Trumbo, on the 60-day IL after undergoing right knee surgery. The club also selected the contract of Jesus Sucre, who will form a rotation behind the plate with recently-acquired Pedro Severino. Elias also left the door open for potential additions through the waiver wire, but barring those, the Orioles will open at Yankee Stadium with the group of 25 they left Sarasota with Monday afternoon.

They aren’t required to officially set their Opening Day roster until noon ET on Thursday.

"We’re all ready for it. We’re ready for the real thing to start for sure. I’m really excited," Hyde said of his upcoming managerial debut. "[Spring] was just practice runs ... Now it’s the real deal.”

The club plans to arrive in New York with three Rule 5 Draft picks, 12 pitchers and plenty of questions regarding how to arrange those arms. David Hess and Mike Wright Jr. will join Cashner and Dylan Bundy in the rotation, but the O's haven’t committed to any order after Cashner starts on Thursday. Righties Jimmy Yacabonis and Pedro Araujo and left-hander John Means are all candidates to provide length in what figures to be a piecemeal effort to cover innings in the early going.

“The Cobb situation [probably forces] some creativity,” Elias said. “I hope that we settle into a situation where we have more regular starters, but I think you’ll see some creativity early, with a couple of bullpen games, maybe a pseudo-opener kind of thing going on.”

On the position player side, Rule 5 Draft picks Richie Martin and Drew Jackson have won shortstop and super-utility jobs, respectively. Rio Ruiz claimed the third-base spot from Renato Núñez, who remains in tow as Trumbo’s replacement at designated hitter. Newly-acquired Dwight Smith Jr. forms a likely platoon in right field with Joey Rickard, after both enjoyed red-hot springs. Trey Mancini and Chris Davis are both options to see at-bats at DH, in addition to their everyday duties at left field and first base. Cedric Mullins will start in center field.

Mychal Givens, Richard Bleier, Miguel Castro and Nate Karns anchor a relief corps that could see significant turnover, given how thin Baltimore is on the starter front minus Cobb.

The Orioles' unofficial 25-man roster, in full:

Catchers (2): Jesús Sucre, Pedro Severino

First base (1): Chris Davis

Second base (1): Jonathan Villar

Shortstop (1): Richie Martin

Third base (2): Rio Ruiz, Renato Núñez

Utility (2): Drew Jackson, Hanser Alberto

Outfielders (4): Trey Mancini, Cedric Mullins, Joey Rickard, Dwight Smith Jr.

Starting pitchers (4): RHP Andrew Cashner, RHP Dylan Bundy, RHP David Hess, RHP Mike Wright Jr.

Relief pitchers (8): RHP Mychal Givens, LHP Richard Bleier, RHP Miguel Castro, RHP Nate Karns, LHP Paul Fry, LHP John Means, RHP Pedro Araujo, RHP Jimmy Yacabonis