SAN FRANCISCO -- As much as right-hander Josiah Gray wanted to continue consistently making every start, he knew something was wrong in his bullpen session. He felt "a little more banged up than usual" following last Thursday's start against the Pirates, and the discomfort persisted.

The fourth-year starter alerted the Nationals medical staff. An MRI revealed a right elbow/forearm flexor strain, and Gray was scratched from his scheduled start and placed on the 15-day injured list on Tuesday, retroactive to Saturday.

Right-hander Joan Adon was called up from Triple-A Rochester to start in his place in the team's 5-3 win over the Giants at Oracle Park on Tuesday night.

"The MRI was a good result," Gray said. "Everything was intact -- the UCL was intact, all the other forearm muscles were intact. … Overall, a positive outlook."

Gray's plan is to rest while the inflammation subsides. He has avoided injuries in his Major League career, last missing six to seven weeks because of a shoulder injury in 2021 while in Triple-A with the Dodgers organization.

"It's sort of a dull linger on the muscle, on the pronator flexor mass muscle," Gray, 26, said. "[It's] sort of a common thing for pitchers. The training staff is going to take care of it and take care of me."

Manager Dave Martinez was glad the All-Star spoke up as quickly as he did rather than trying to pitch through it and risk further injury.

"He was great about it, he really was," Martinez said. "As you know Josiah, he's going to do whatever he can to get better. But he was very, very positive."

Gray, named the 2024 Opening Day starter, has made 72 starts for the Nats since being acquired from the Dodgers at the 2021 Trade Deadline. In two appearances this season, he is 0-2 with a 14.04 ERA in 8 1/3 innings. This is his first stint on the injured list in his career.

"It sucks," Gray said of missing playing time. "Ever since I joined the Nationals, I made every single start that I was scheduled to make and I prided myself on doing that. So, obviously, it's a little bit of a gut punch to come to the ballpark and not be slated in the five-man rotation for the foreseeable future.

"It's a harsh reality of what we do as pitchers, especially in today's game. Injury risk is going up. It definitely gives you a sense of reality in what we do. Unfortunately, I have to miss some time, but I don't think it's going to change anything I really do. Obviously devote some more time to recovery and stuff like that. But I'm going to turn a corner from this and come back strong."

Adon, 25, was with the Nationals' taxi squad for their three-city West Coast road trip. He has made 27 big league appearances (25 starts) with the Nationals since 2021. Last season, he went 2-4 with a 6.45 ERA and 48 strikeouts in 51 2/3 innings. Adon was with the Nats in big league Spring Training and has made one start for the Red Wings this season. Emphasis will be placed on Adon's mechanics and direction.

"I think he deserves a chance to come up here and try to help us win a game today," said Martinez. "We'll see how he goes out there. I know he's got a good game plan. He came in yesterday. We sat down with him and talked to him about what we're looking for from him, so he's going to go out there and compete."

In addition to Adon, Triple-A right-hander Jackson Rutledge, the Nationals' No. 15 prospect per MLB Pipeline, is a candidate to make Major League starts if needed. Rutledge debuted on Sept. 13 last season and made four starts with Washington.

"I want him to get a few more starts before we decide what we're going to do," said Martinez. "I want him to go out there and really feel good about himself. He's throwing the ball well."