Ramirez was not in the lineup Friday and Mattingly said even if the MRI comes back with good news, he would still be careful playing his shortstop over the last 16 games of the regular season.
"We don't have to push him out there at this point," Mattingly said.
Ramirez left Thursday's game in the seventh inning against the Giants after notifying trainers the hamstring had tightened up.
"Honestly, the things we've been hearing the last couple of days are really the things we've been hearing for two, three weeks," Mattingly said. "It's not like all of a sudden. It just got a little farther than I think we were comfortable. We're trying to be on the cautious side, making sure it didn't go anywhere."
"If it's any kind of extended period of time, [then] we gotta take care of Nick too," he said. "What we found out is if we go too many days in a row with Nick, then you end up having Nick with a problem too."
Mattingly said he hadn't been particularly nervous playing Ramirez the past few weeks, because the hamstring had some soreness since he spent a month on the disabled list with the original strain.
"Since he's come back from the hammy, there's always been a little tightness there we've always paid attention to," Mattingly said. "We've been doing this basically since he came back."
It sounds like the hamstring never completely healed, but Mattingly was still trying to be optimistic Friday.
"I know Hanley was feeling good about everything that was going on," he said. "We just have to be sure."