"They don't seem too concerned, but they are going to do an MRI for precautionary measures," McClendon said. "Hopefully he should be OK. But I would say it's highly unlikely that he'll make his next start."
Elias is scheduled to face the Astros on Sunday in Houston and remains confident he'll be able to pitch.
"It started when I threw a changeup," the Cuban native said through an interpreter. "It felt a little tight, so I started talking to Felix [Hernandez] and he talked to the manager and that's what they decided to do. I've never felt that [before], but I'm not scared. I'll keep working and be ready for Houston."
The Mariners were trailing the Angels, 2-0, at the time, with Elias having allowed five hits and a walk with one strikeout. The southpaw is 10-12 with a 3.85 ERA in 29 starts and his 163 2/3 innings are the second-most of any rookie in the Major Leagues this year.
Elias was pitching on an extra two days of rest as the Mariners attempted to monitor his workload, having already reached the highest innings total of his professional career. But he was expected to stay in the rotation on regular rest for two more starts in the final two weeks.
He insists the elbow situation isn't the sign of the mounting innings.
"No, no. I'm not getting tired," he said. "It's just part of the game and I'll keep working hard."
Elias is 3-4 with a 2.31 ERA in 10 starts in the second half and has been a key component in a starting rotation with the lowest ERA in the American League.
"He's pitched extremely well, particularly since the All-Star break," McClendon said. "He's done a fantastic job for us. It's unfortunate he doesn't have a better record to show for it, but I don't think what he's done has gone unappreciated. This young man has a bright future and we want to make sure we protect him."
Seattle does have another starter available with top right-handed prospect Taijuan Walker currently working in the bullpen as a September callup.
"We haven't talked about any of that stuff," McClendon said. "We'll see how things unfold."