How Julianna Margulies Went from a 'Flunked' ER Audition to Having Her Fate on the Show Reversed Thanks to George Clooney

It's really a miracle that Julianna Margulies' landed her career-launching role in ER — let alone kept it going for six years.

Margulies, 58, played fan-favorite nurse Carol Hathaway on the medical drama, and on the Nov. 8 episode of The Kelly Clarkson Show, she revealed just how unlikely the series of events was that led to her getting on the show.

She recalled having three auditions on the day of her audition for ER, and, thanks to her "hippie, crazy, wonderful mother who was always late," Margulies has a penchant for arriving early.

"So I got to ER — I had 2 other auditions afterwards — and there was probably 50 people in the waiting room and they were running two hours behind and I was pissed," she said. "I was like, 'I'm gonna be late for my other auditions, this is not OK. Forget it.'"

Right around the two-hour mark, Margulies said she was "walking out" when the casting director called her name, and she reluctantly went in to read for a recurring character.

"But I was so pissed off that I did it really rudely — a little New York anger. And I knew I flunked," she said. "And I walked out of the audition and the casting director said, 'Hold on a minute. You're not right for the part.' And I was like, 'Ya think?' And he said, 'But you might be right for this head nurse Carol Hathaway, but she dies in the pilot. But could you come read for that?' So I went back in and I read for Hathaway, with a lot of attitude. And I got the role."

In the original pilot script, Carol died from a drug overdose, Margulies recalled, and it was an emotional moment as it was seen "through George Clooney's eyes" because Carol was "an old flame" of his character, Doug Ross.

"So suddenly her death seemed really important to the audience watching," she said.

After showing the episode to a test audience, though, Carol's death was reconsidered. "When the character died, the whole audience went, 'No!' Because they love George Clooney so much — who doesn't?" she said.

There was one final coincidence involved in the pilot episode that squarely set up Margulies' six-season run on ER, another "confluence of events" as she described it to Clarkson.

Sherry Stringfield, who played Dr. Susan Lewis, was in the operating room when Margulies' character was brought in on a gurney, but she "put her clipboard up to her mouth when she said, 'She's braindead.' So you don't see it."

"So they just looped different lines in saying, 'She's gonna be okay,' or whatever. And they brought me back to life," Margulies said.

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The bond between Margulies and Clooney, 63, is still strong to this day. Ahead of the actor's upcoming Broadway debut in Good Night, and Good Luck, Margulies told PEOPLE she's "given him a lot of kudos" on the role.

"I just emailed him and said, 'I'm so proud of you. You don't have to do this,'" she said. "It's scary, you know, being on Broadway... And so I'm really proud of him for picking a hard road. It's not easy work, and I'm really impressed that he's doing it."