Nearly 15 months after undergoing Tommy John surgery, Chris Sale says he is confident he will be ready to contribute to the Boston Red Sox before the end of the season.

"One hundred percent," Sale said Tuesday before knocking on a wood table in front of him. "Unless something crazy happens. I'll be there soon enough."

Sale returned to Fenway Park on Monday and was spotted throwing in the outfield. He threw again Tuesday, with manager Alex Cora saying the Red Sox ace threw 25 pitches, including a combination of his fastball, changeup and slider.

Sale last appeared in a game in August 2019 and is itching to make his return to the mound.

"If it was up to me, I'd be starting tomorrow," he said.

Sale will remain with the team through at least the end of next week, continuing to throw bullpen sessions with the major league squad after spending months rehabbing at the spring training complex in Fort Myers, Florida.

"He's in a great place mentally," Cora said. "Physically, he looks a lot stronger than two years ago. Just excited that he's a baseball player again. Now we've just got to be patient. ... It felt good to see him, to have him around, and now we get excited but at the same time, we have to be disciplined, we have to be patient and whenever he's ready, we know he's going to contribute."

The next step for Sale in the rehab process would be throwing against hitters while he's with the team in Boston. Head trainer Brad Pearson and pitching coach Dave Bush compared the intensity of Tuesday's bullpen session to one a pitcher would go through in January.

"Basically, they said don't get too excited," Cora said.

Expressing his desire to return to competitive games, Sale said he would be willing to pitch out of the bullpen in order to build back toward being a starting pitcher if it meant skipping rehab starts in the minor leagues.

"I would be game for that," Sale said. "The quicker that I can be back on this team, I would like that. That is way above my pay grade and where I'm at right now. I'm focused on my next day and getting off the mound and then whatever the next step is, take that."

Sale said that he was both pleased and not pleased with the progress of his rehab.

"I'd like to be out there already," Sale said. "From where I started in spring training to where I am now, I've done everything I possibly could to put myself in the best position. I've had a lot of help through this process. A lot of people guiding me and getting me through this. So I've been very pleased with what has been going on and where I'm at."

The time away from the field gave Sale a new appreciation for the mundane things a baseball player works through on a day-to-day basis while preparing during the season.

"I can already tell that I appreciate what I do on a daily basis more than I ever have in my life," Sale said. "If it's coming here and doing a shoulder program -- which I don't know if I ever heard of a pitcher who liked doing a shoulder program -- but just appreciating the fact that I get to do it, just being able to throw, that I've been able to throw the last few months and it's not going to be some big ceremonial game."