Bill Clinton told Charlie Rose that his wife apparent collapse or stumble, as it is being described, at a 9/11 memorial ceremony in NYC has happened before when she became “severely dehydrated.”

“Rarely, on more than one occasion over the last many, many years, the same sort of thing’s happened to her when she got severely dehydrated,” Bill Clinton told Rose about Dem presidential nominee Hillary Clinton. “And she’s worked like a demon, as you know, as Secretary of State, as a senator, and in the year since.”

Rose has interviewed the former president in the wake of his wife’s dramatic departure from the 9/11 memorial yesterday and her doctors’ subsequent announcement that she has pneumonia.

In addition to trying to calm jittery voters with this interview, Bill Clinton is stepping in for his pneumonia-plagued wife at tomorrow’s pricey fundraisers set for Seth MacFarlane and Barry Diller’s homes, campaign sources confirm to Deadline.

A portion of Rose’s interview with the former POTUS will air tonight on CBS Evening News with Scott Pelley, the full interview will air on Charlie Rose on PBS and the interview will be featured on CBS This Morning on Tuesday.

In the interview, Bill Clinton insists his wife is “doing fine” and “just got dehydrated yesterday.”

Rose seemed somewhat dubious, saying the video of what appears to be Hillary Clinton’s “collapse” left him wondering “if it’s not more serious than dehydration.”

“Well, if it is then it’s a mystery to me and all of her doctors,” Bill Clinton shot back, leading into his been-there-done-that explainer.

Rose noted that Hillary is older than when Bill Clinton ran for office.

“And she had 2 1/2 hard days before the day when she got dizzy,” he replied. “Today she made a decision, which I think was correct, to cancel her campaign day to take one more day to rest.”

He added there is “not a shot” she will stand down from campaigning for “weeks” as Rose suggested, adding, “I’ll be lucky to hold her back another day.