Terry Collins reiterated his concern about Jason Bay, who is on the seven-day DL with a concussion.
"I'm really worried about him," Collins said Sunday.
The Mets skipper said Bay will rest over the weekend before likely seeing a doctor Monday.
Asked about the possibility of Bay missing the rest of the season, Collins responded, "anything's possible."
Bay missed the final two months of 2010 after suffering a concussion.
Collins said he feels terrible for Bay, who hasn't lived up to the expectations that came with his four-year, $66 million deal.
• Collins said Ruben Tejada will begin a rehab assignment at Triple-A Buffalo on Monday. Tejada has been out with a quadriceps injury.