"The disabled list is a good possibility," Padres manager Bruce Bochy said after his club's 2-1, 10-inning win over Arizona -- which left the Padres four games behind the Dodgers in the NL West going into a three-game series with Los Angeles starting Monday night at Petco Park.
Young, who is 9-5 with a 3.77 ERA over 25 starts, felt a "tightness" in his right shoulder on his penultimate warm-up pitch in the bullpen.
"It was never painful," Young said. "It felt like a spasm. And everything around it was tight. Obviously it was restricting me. But I never thought once about not taking the mound before the game."
Young's average velocity is between 88 and 92 mph. Over the course of the 12 pitches he threw in the first inning Sunday, Young never topped 84.
"I could see my ball sinking when I threw it," said the 6-foot-10 right-hander. It was not a good sign. "I don't have a sinker. And this was gravity-induced sink. I didn't even want to look at the board for my velocity."
Young will be re-evaluated Monday before the Padres make a decision about putting him on the disabled list.
Said trainer Todd Hutcheson: "It's not the typical problem you usually see in the shoulder. But it's muscular and doesn't involve tendon or ligaments. In that respect, it's not major."