The days leading up to her birthday weren’t happy ones for Liza Minnelli.

Weakened and in pain from the back and hip problems that have plagued her for years, the star had been drinking when she fell and hit her head.

“It wasn’t serious,” confides a good friend of the star to ‘Closer,’ “but Liza joked that a knock in the head may have been just what she needed.”

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Liza at the Oscars in March 2014.

Not long after, the show business legend voluntarily checked into an undisclosed Malibu rehab facility where she spent her 69th birthday on March 12 — and it may have been just in time.

Related Story: Happy 69th Birthday, Liza Minnelli — Plus See 13 More of Hollywood’s Most Famous Celebrity Children!

“She found herself drinking first thing in the morning and it got really bad. She would drink all day and then forget to eat,” confides the friend. But Liza pulled the emergency brake herself. “She said, ‘I’ll be dead if I don’t get help — simple as that. I need to clean up my life or I’m going to be buried by the time I’m 70,’” reveals the friend.

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Liza with her mother, Judy Garland, in 1962.

Of course, the star has been down this road before. She’s been to rehab multiple times, says the friend, and this trip comes nearly 11 years after her last in-patient treatment.

“Liza knows what to do to get healthy,” says an insider. Adds the friend: “You have to give her credit, she never gives up. She keeps trying to finally get well for good.”

To read the full story on Liza, pick up the new issue of ‘Closer Weekly,’ on newsstands now!