Chamberlain missed his fourth consecutive game in Thursday night's 7-5 loss to the Red Sox to be with his stricken father in Nebraska. The hard-throwing reliever left the team Monday and was placed on the bereavement list, a day after Harlan Chamberlain collapsed at home.
New York manager Joe Girardi said he spoke to Chamberlain on the phone Thursday.
"His dad is continuing to do better. He was up to rehab twice today," Girardi said. "There's still no timetable, but there is progress and that's a good thing."
Girardi isn't sure when his setup man will rejoin the Yankees, who were set to play the finale of a two-game series against Boston on Thursday night.
Players on the bereavement list must be inactive for at least three days and a maximum of seven. If Chamberlain isn't ready to return to the team after seven days, general manager Brian Cashman and the Yankees can reapply to the commissioner's office for another stint.
"I hope it doesn't come to that. But if it does, Cash will do what he has to do," Girardi said.
Also on Thursday, catcher Jorge Posada said his ailing throwing arm felt better and he hopes to be behind the plate Saturday in Baltimore. Posada hasn't started at catcher since April 8 because of a dead arm.
"I'm pushing for Saturday," he said. "I guess I could have played today. They didn't want me to."
"We have to make sure Jorgie can catch multiple games," Girardi said. "It's a strange kind of injury, and we're just going day by day."