Billy Joel ‘Needs to Pace Himself’ Amid Brain Disorder Battle: Not ‘Completely Out of the Woods Yet’ (Exclusive)

Billy Joel was in a New York state of mind.

On Thursday, March 12, the beloved Piano Man, 76, made a rare appearance amid his brain disorder battle at a sold-out tribute concert in his honor at Carnegie Hall in midtown Manhattan.

“It’s being seen as a very good sign as far as his recovery,” a source tells Closer. “At the same time, everyone close to him knows this is still a very delicate stage and that he needs to pace himself.”

Joel was forced to cancel all his upcoming shows in May after being diagnosed with normal pressure hydrocephalus (NPH). It’s a rare condition — and one that his team explained in a statement was being “exacerbated” by his concert performances, causing issues with hearing, vision and balance.

“Billy is making a big point to downplay this publicly,” the source admits. “He doesn’t want any pity or anyone worrying about him, but that doesn’t mean he’s completely out of the woods yet. You just have to look at him to see how fragile he’s gotten.”

Ex-wife Christie Brinkley is among those who are desperately worried about Joel as he enters a crucial period in his recovery that’s very much make-or-break, says Closer’s source.

“Christie has been keeping a very close eye on him since this all happened,” the source reveals. “She’s always calling to check in and offering help.”

Despite divorcing in 1994, the former supermodel, 72, has remained good friends with the “Uptown Girl” singer, with whom she shares 40-year-old daughter Alexa.

“Christie keeps reminding him that his health has to come first and that there’s no shame in slowing down,” adds the source. “The question is really whether he will actually listen to her advice.”