The severity is unknown at this time, though it's not something that figures to keep him out of Sunday's game against New England. Rice was able to finish Monday night's game against Detroit.
Rice did have a hip flexor injury this season, so it's possible this is related to that.
Here's the full injury report:
DID NOT PARTICIPATE: LB Dallas Clark (illness), CB Asa Jackson (thigh), LB Albert McClellan (neck), RB Ray Rice (thigh).
LIMITED PARTICIPATION: QB Joe Flacco (knee).
FULL PARTICIPATION: S Brynden Trawick (ankle).
NEW ENGLAND PATRIOTS
DID NOT PARTICIPATE: WR Josh Boyce (ankle), OT Nate Solder (concussion).
LIMITED PARTICIPATION: WR Danny Amendola (groin), CB Kyle Arrington (groin), QB Tom Brady (right shoulder), OT Marcus Cannon (ankle), CB Alfonzo Dennard (knee, shoulder), WR Aaron Dobson (foot), LB Dane Fletcher (groin), S Steve Gregory (finger), TE Michael Hoomanawanui (knee), LB Brandon Spikes (knee), OT Will Svitek (ankle), CB Aqib Talib (hip), WR Kenbrell Thompkins (hip).