ATLANTA -- Tyler Glasnow was slated to throw a two-inning simulated game at Truist Park on Friday, a significant step in the right direction to his availability atop the starting rotation in the postseason.

But as Glasnow was about 20 pitches into his warmup before stepping out onto the field, the right-hander complained once again about discomfort in his right elbow. After a quick discussion, the Dodgers and Glasnow canceled the simulated game, a potentially devastating setback for the 30-year-old right-hander.

“He just felt some discomfort in his arm,” said Dodgers manager Dave Roberts. “We felt we should cut it short and couldn’t go through with the sim game. Obviously, it’s a setback. I don’t know what that means as far as the coming days. I just know we’re going to re-assess and see how he feels over the coming days, see where we can pick up throwing again.”

Glasnow will undergo an MRI over the weekend, which should give the Dodgers a better idea of a timetable. But given the Dodgers entered Friday’s game with just 16 games left in the regular season, Glasnow’s regular season has likely come to an end. His postseason availability is now also in question.

“I don’t know if we have margins anymore. It’s unfortunate,” said Dodgers pitching coach Mark Prior. “We’ll see where he’s at tonight and tomorrow morning. I can’t really speak to where we’re at with anything because I really don’t know other than, by not throwing today, that’s a concern and a red flag. … Maybe it’s a hiccup and we can continue. But there’s also a chance that it might not be and obviously it’ll be devastating.”

Glasnow, who signed a five-year, $136.5 million extension after being acquired from the Rays this offseason, was brought in to be one of the top pitchers in the rotation. The right-hander surpassed his career high in innings with 134 innings this season and made his first All-Star team in the first half, but he landed on the injured list in mid-August a day before making his scheduled start against the Cardinals in St. Louis.

Over the course of his career, Glasnow has dealt with right elbow and forearm injuries that have cut his season short. But after undergoing Tommy John surgery in ‘22, Glasnow and the Dodgers were confident those issues were behind him.

The Dodgers will now have to weigh his previous injury history with his availability the rest of the way.

“It’s a big part of the equation,” Roberts said. “So obviously where we’re at in the calendar -- but his health is most important. How we build him up, how we get him pain-free, all those are conversations he’s got to have with the training staff to see where we’re at. All I know right now is that we couldn’t finish the simulated game today. That’s telling in a lot of senses.”

With Glasnow now likely unavailable to start the postseason, the Dodgers will need others to step up in the rotation. Jack Flaherty and Yoshinobu Yamamoto are the team’s best two options. Behind them, there are some real question marks.

Clayton Kershaw and Gavin Stone are still recovering from their respective injuries and it’s unclear when or if they’ll return this season. Walker Buehler is an option now for the Dodgers, as is rookie Landon Knack.