"After several difficult days, my father is feeling much better," Chamberlain said in a statement released by the club. "He is still in the critical care unit of the hospital and more tests await him, but he is off the ventilator and breathing on his own. Each day he's acting more and more like himself, and he's even giving people grief -- myself included -- because the hospital doesn't carry Yankees games on television."
Meanwhile, Yankees manager Joe Girardi said that Chamberlain has thrown two side sessions while in Nebraska -- the most recent was on Thursday -- in an attempt to remain sharp.
"His father's obviously doing better, so that's a great thing," Girardi said before the Yankees opened a three-game series at Camden Yards with the Orioles. "I think we're closer to getting him. The exact date? I don't know. The time has to be right for Joba, and I've told him that all along -- you make sure you're comfortable with where your father's at before you rejoin us."
Chamberlain is eager to rejoin his Yankees teammates and thank them for their unwavering support during his unplanned absence.
"When things like this occur in life, you certainly take notice of how much your teammates become more like family members," Chamberlain. "Their unconditional support, along with that of so many fans, has made a very tough time easier to deal with. Everyone's love has been felt by my entire family, and it has brought great comfort to us when we have needed it most."
Chamberlain, 22, left the Yankees on Monday upon receiving word that his father was critically ill at St. Elizabeth Regional Medical Center in Lincoln. Harlan Chamberlain collapsed at his home earlier that day, and he was placed on a ventilator to help him breathe upon arriving at the hospital.
Chamberlain was placed on the bereavement list on Monday, making him ineligible to play for a minimum of three days.
Girardi has been in frequent contact with Chamberlain and has relayed reports of his father's medical condition on a daily basis. Girardi had hoped to have Chamberlain, who is 1-0 with a 0.00 ERA in five relief outings this season, by the end of this week, but that timetable remains in flux.
Girardi didn't rule out a return this weekend, but he didn't endorse the idea, either.
"As I said, he'll be back when he's mentally ready," said Girardi.
Harlan Chamberlain has a long history of health problems, and a childhood case of polio left him partially paralyzed. He relies on a motorized scooter for transportation. He and his son are very close and speak on a daily basis during the regular season.
Joba Chamberlain said he has been overwhelmed by the outpouring of support from his teammates and Yankees fans during his time of need.
"I look forward to being reunited with my manager, coaches and teammates so I can thank each of them personally for all that they have done for my family," he said.
Pete Kerzel is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.