FORT MYERS, Fla. -- The Red Sox revealed on Thursday that ace Chris Sale has a flexor strain in his left elbow and will wait a week before he throws again.

On the surface, that sounds encouraging given the initial fears a couple of days ago that Sale could need Tommy John surgery.

However, both the Red Sox and Sale were open about the fact he isn’t out of the woods yet.

The litmus test will be how Sale responds to throwing again. The progression, if Sale doesn’t have any adverse symptoms, would be catch, then bullpen sessions and live batting practice.

Only once Sale clears all those hurdles will the lanky lefty know if he can be a significant contributor to the 2020 Red Sox.

After spending all winter rehabbing the left elbow injury he endured last August, which knocked him out of the final six weeks of the 2019 season, Sale is understandably downcast that his elbow is barking again.

“Obviously [I] don’t want to be sitting here giving you this information,” Sale said. “But yeah, [it’s a] tough spot for myself, this team, and this organization going forward.”

The uncertainty is the hardest part -- for both Sale and the Red Sox.

“I’ve done what I’ve done and I’m at where I’m at, and moving forward I just can do everything I can do to make this better and get back out there and help this team win,” Sale said. “That’s where I’m at. I can’t read the future, all I can do is work my ass off to get back out there as soon as possible, whenever that might be to get back to doing what I’m supposed to do, what this team needs me to do and what I’m expected to do.”

Sale acknowledged that if things don’t go well during the build-back-up period of throwing, Tommy John surgery could wind up being on the table.

“That’s what we determine in two or three weeks. It’s a tough situation. I’m only telling you everything I know,” said Sale. “That’s all I got. I’m going to know a lot more in two or three weeks. As soon as I figure that out, I’ll be sitting right here in front of you waiting for it. That’s all I can do.”

It was just under a year ago that the Red Sox rewarded Sale with a five-year, $145 million contract extension that kicks in at the start of this season. After being a dominant ace for nearly his entire career, very little has gone right for Sale since he signed the contract.

“That’s my biggest issue. That’s what makes it tough to sleep,” said Sale. “I know, like I said, I know what I mean to this organization, to this team, the success going forward. And I know the faith they put in me. That’s evident in the press conference I had in Spring Training last year with the contract. I couldn’t possibly feel worse about any situation I’ve ever felt in my entire life because of that. Plain and simple.

“I don’t think I’ve ever let anybody down this hard, ever. Honestly. Someone gives you something because they believe in you, they expect something from you and you don’t live up to that.”

The 2019 season -- even before the elbow started bothering him -- was the worst of Sale’s career. He went 6-11 with a 4.40 ERA in 25 starts.

“There’s an expectation level that ... our fans, my team, you guys, and myself hold me to and I haven’t met that,” said Sale. “I haven’t. This is about as tough a situation I’ve ever been in. I was able to get through most of my career doing what I love to do and helping my team win. For sure, over the last year and up to this point, I’ve done nothing but fall flat on my face.

“So that’s a gut punch and a tough realization. But I’ve said time and time again I have no time to hang my head and sit in the corner and pout. I’ve got work to do and I’ve got an uphill battle to climb, but I’ve got my climbing shoes on. So I’ll be ready to roll whatever way we’ve got to go.

The Red Sox and Sale revealed their diagnosis after conferring with two of the most renowned surgeons in sports -- Dr. James Andrews and Dr. Neal ElAttrache.

The consensus was that Sale’s UCL presented the same way in the images as the MRI he had last August.

“Everybody thought with the imaging that this is the way we should go with this,” said Red Sox interim manager Ron Roenicke. “They thought, 'Let’s give it a try and see where we are, and hopefully he’s right back on track and this was just a setback and we can get him to continue and get through the year and hopefully years to come.'”

Sale will start the season on the injured list and, at minimum, would likely miss the first few weeks of the season. When does Sale think he can start a game for the Red Sox again?

“I can’t tell you that. I’ve sat before you now hundreds of times, I would assume, right? And I’ve only ever given you everything I know,” said Sale. “I’m going to continue to do that. I will know more in a couple of weeks from now because as of now, I’m shut down.

“I can’t tell you how it feels. I can’t tell you what the process is until I pick up a baseball for the first time. As of right now, I’m just spinning my wheels.”

Meanwhile, the Red Sox, who traded David Price to the Dodgers last month along with Mookie Betts, will start the season with great uncertainty in the rotation.

Eduardo Rodriguez, coming off a 19-win season, will try to be the ace, something he’s never been asked to be before. Flame-throwing Nathan Eovaldi, who was injured and inconsistent last season, will try to rebound. Lefty Martín Pérez will try to be the pitcher he was for the Twins through July 17 of last season (8-3, 4.10 ERA) rather than the one he was after that date (2-4, 6.72 ERA).

On Thursday, the Red Sox signed swingman Collin McHugh to a one-year contract, but he is coming off a flexor strain of his own from last season and hasn’t even started his Spring Training throwing program yet.

The pool of starting candidates for the No. 4 and No. 5 spots includes Ryan Weber, Brian Johnson, Chris Mazza, Tanner Houck and Thursday's starter, Kyle Hart, among others. Roenicke is considering using an opener for one or two spots in the back of the rotation.

At this point, the club plans on keeping the electric left arm of Darwinzon Hernandez in the bullpen, though he could factor heavily into an opener scenario. Roenicke even hinted he could go back to starting at some point this season, but the Red Sox are being conservative about moving him back and forth between roles too often.

In the meantime, the Red Sox hope for an impactful Sale at some point in 2020, knowing it will be tough to make the playoffs without him.

“This guy is one of the top five pitchers in the game and that’s what we’re hoping to see through his contract,” said Roenicke.

Nobody -- not any club executive, coach or teammate -- is hoping for that as much as Sale himself.

“Just like every other process I’ve ever been in, healthy, not healthy, the best I’ve ever been, and the worst I’ve ever been, I’m going to do it the best I can and get after it,” said Sale. “And however the coin flips, that’s how we pick it up.”