"It's always a concern any time you get a guy banged up in Spring Training," manager Mike Redmond said. "Being that it is so early, I'd rather have it now than two weeks left in Spring Training before the season starts.
"At the same time, too, those backs can be touchy. Sometimes they take a little time. We have to make sure that he's healthy and ready to go for the long run, and not just Spring Training games."
Projected as Miami's starting center fielder, Ruggiano tweaked his lower back while fielding a ground ball in the outfield on Thursday. He had an MRI taken later in the afternoon.
"I'm not sure how long he is out," Redmond said. "He is getting treatments. We'll just have to see day-to-day, how that progresses."
On Friday morning, Ruggiano still felt tightness in his lower back. "It feels the same," he said.
The Marlins open their Grapefruit League schedule on Saturday against the Cardinals. Gorkys Hernandez will get the start.
Other center field possibilities include Chris Coghlan, Bryan Petersen and Kevin Mattison. The Marlins have prospects Christian Yelich and Jake Marisnick as well, but both are expected to open the season at Double-A Jacksonville. They will likely see plenty of game action early in camp.