Francisco Cervelli has started to work out but has not been cleared to resume baseball activity. He visited a neurologist on Friday.
Cervelli suffered a concussion as a result of a collision at home plate on Sept. 8 in Baltimore.
He has not played since that day due to the lingering effects of the concussion, the third one Cervelli has suffered in his career.
He underwent an IMPACT Test on Monday, which compares results with tests taken when his head isn't affected by an injury. Cervelli is also scheduled to see a neurologist on Friday.
"He's still experiencing symptoms so I'm not sure we're going to get him back," Joe Girardi said, giving the strongest indication to date that Cervelli will not be available for the postseason.
Cervelli, hitting .266 with four home runs and 22 RBIs. He may not be replaced on the postseason roster, however, because Girardi indicated that Russell Martin can start behind the plate for the entire postseason.
In that case, Jorge Posada and Jesus Montero would serve as emergency catchers.