SCOTTSDALE, Ariz. (AP) -- The Colorado Rockies' first full-squad workout was missing a key arm.
Jhoulys Chacin, the team's top right-handed starter a year ago, was shut down Sunday because of inflammation in his throwing shoulder.
He's scheduled to undergo an MRI on Monday.
''I feel good about the fact that we caught it early,'' Rockies manager Walt Weiss said. ''He's had it at times in the past. Not necessarily last year, but I think the year before. So we're being really cautious with it. It's the first day of camp, so we've got time on our side.
''We'll hope for the best, but I'm not overly concerned right now, just because it's February,'' he said.
Chacin had been limited with his throwing in the first few days of camp.
''It sounds like it's something he tried to pitch through in the past and it kind of lingered and lingered,'' Weiss said. ''So we're trying to get ahead of it.''
Chacin was Colorado's most reliable pitcher in 2013, logging a team-high 197 1-3 innings. The 26-year-old went 14-10 with a 3.47 ERA and allowed only 11 home runs despite playing home games in hitter-friendly Coors Field.
But the Venezuela native had arm problems in 2012, when he was limited to 14 starts.
On a staff without a true ace, Chacin and left-hander Jorge De La Rosa top Colorado's rotation. Weiss indicated it was too early to rule out Chacin as a possible opening-day starter.
''We'll know in the next few days or a week when we have a better idea how serious it is,'' Weiss said.
Chacin and right-hander Wilton Lopez (stiff neck) were the only players to sit out as the Rockies held their first workout Sunday with all position players present.
Weiss, beginning his second season and armed with a new three-year contract, addressed the team Sunday morning and said he focused on creating a winning identity.
The Rockies went 74-88 last season, a 10-game improvement from Jim Tracy's final season as manager in 2012. Colorado last made the playoffs in 2009.
''Effort, I'm not too concerned with in this group,'' Weiss said. ''These guys are going to show up every day. But on top of the effort you've got to play the game right. It's the execution I was talking about.''
One player happy Sunday was Carlos Gonzalez. After Weiss initially told the three-time Gold Glove left fielder he'd move to center, Weiss changed his mind.
Gonzalez is back in left, with newly-acquired Drew Stubbs leading a group competing for the starting job in center vacated when Dexter Fowler was traded to Houston.
''It was the first time in a while I didn't know where I was going to play,'' Gonzalez said. ''It's always in your mind. I'm happy to be back in left field. That's where I've been playing for the past three years.
''They knew that playing center field was going to take a lot from me,'' he added.