The Ravens have three starters - safety Ed Reed (groin), offensive tackle Jared Gaither (foot) and linebacker Tavares Gooden (groin) - who are listed as doubtful for Sunday's game at Pittsburgh.
Reed, who didn't practice all week, ran off to the side with his helmet on before practice. Asked about Reed's recent visit to a specialist, coach John Harbaugh said it was good news because it confirmed the team's treatment.
"We have a very good handle on what it is," Harbaugh said Friday. "It's going to be a matter of him being able to go as soon as he can, which could be as early as Sunday. It's really one of those wait-and-see injuries."
Harbaugh said placing Reed on injured reserve is "not in the equation."
Tom Zbikowski is expected to replace Reed for the fourth straight week.