"As soon as I took the swing, I felt something in my shoulder," Rojas said. "I think I irritated my right shoulder a little bit. Right now I'm day to day. We'll see how it feels tomorrow, and I hope I can play through it."
Derek Dietrich entered at second base in the fourth inning. Dietrich was back playing a day after he was struck by a foul ball in the back of his head on Sunday in a 7-3 win at Atlanta.
• Dietrich relieved to avoid serious injury
"They're calling it shoulder irritation right now, and minor," manager Don Mattingly said. "They think he's going to be OK."
The Marlins are hopeful Rojas may be out just a few days and can avoid a disabled list stint. No X-ray was taken, but Rojas will be re-evaluated on Tuesday morning.
"It's something they took me out as a precaution thing," Rojas said. "We'll see how it feels tomorrow. Throwing is not a big deal; it's just when I swing the bat. I gotta see tomorrow if I can do it."
Rojas, batting .268, is one of Miami's most versatile players. He offers depth at all four infield positions and frequently has been used at first base as a defensive replacement in the late innings.
"As soon as I swung the bat, I felt something on my shoulder," Rojas said. "Donnie approached me in the dugout and said, 'Hey, try to not to risk anything and we'll take you out of the game.'"
Being without Rojas also means the club doesn't have a natural backup shortstop in case something happened to Adeiny Hechavarria. Dietrich did play shortstop in college, but not the big leagues.
The Marlins have been shorthanded already with Giancarlo Stanton being out since last Wednesday. The club is hopeful the slugger, who is dealing with right side soreness, can return in a couple of days.
"It's just where we're at right now," Mattingly said. "We just have to try to survive this little period of time. You feel like within a few days here, we're going to get back to pretty much full strength, we're hoping."