Mercurial defensive tackle Albert Haynesworth missed practice Saturday for the second straight day, the Boston Herald reported.
The team has yet to disclose the reason for Haynesworth's absence.
New England acquired Haynesworth in a trade with the Washington Redskins in July for a 2013 fifth-round pick.
Disgruntled in Washington, Haynesworth told reporters this week that he hopes to keep his history of troubles on and off the field from resurfacing with his new team.
"Albert has worked hard. I think that it's coming," Belichick told reporters Tuesday. "We've got a long way to go, so just take it day-by-day, but I think he's doing fine."
The Associated Press contributed to this report.