Don Murray will never forget his experience working alongside America’s most iconic sex symbol.

The now-89-year-old starred alongside Marilyn Monroe in 1956’s “Bus Stop,” about a stubborn cowboy who falls head over heels for a saloon girl and then tries to take her away against her will to get married and live on his Montana ranch. While the actress captivated audiences with her great beauty and talent on-screen, Murray revealed she suffered from crippling anxiety.

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“She was very, very nervous,” Murray recalled to Closer Weekly in the magazine’s latest issue on newsstands. “She’d break out in a rash every time we’d shoot a scene.”

American actors Marilyn Monroe and Don Murray on the set of "Bus Stop," directed by Joshua Logan. (Sunset Boulevard/Corbis via Getty Images)

According to the magazine, Monroe’s rashes got so bad that makeup artists were called in to hide her blemishes. However, it was difficult for them to make the distressed actress look flawless during certain scenes.

“We had a scene where she was naked in bed, and she kept rolling around and accidentally exposing herself,” recalled Murray.

The issue became so persistent, director Joshua Logan allegedly pleaded with Murray and said: “Whenever she moves, slip your hand and cover her.”

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The actor said he tried his best to make Monroe feel at ease on set, but bringing “Bus Stop” to life wasn’t always smooth sailing.

1956: American actress Marilyn Monroe (1926 - 1962) adjusts her make-up, using a handheld mirror on the set of director Joshua Logan's film, "Bus Stop." She is standing next to a movie camera in a crowd of people. — Photo by Hulton Archive/Getty Images

“After the first day of shooting, Joshua came to me and said, ‘Marilyn has a tendency to miss her marks,’” said Murray. “He told me, ‘Whenever she’s off her mark, put your hands on her hips and move her.’”

Murray claimed that every time he attempted to move Monroe a little bit to the left or right, the star would get angry with him.

And during one scene, things nearly escalated.

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“[Once] she swung the sequined tail of her costume across my face and it cut my eyelid,” said Murray. “She stalked off the set, and I started after her. I was going to tell that spoiled brat where to get off, but Joshua said, ‘No, I’ve won the war by avoiding these battles.’”

Monroe, who had a hard time keeping up with her co-stars, brought in Paula Strasberg, her colleague from New York City’s Actors Studio, for much-needed support.

“Paula would watch and listen and give Marilyn advice between takes,” said Murray. “She was friendly and nice and a very good influence on Marilyn… [But] she would lose track of scenes very quickly, so they had to put her performance together out of small pieces. You never got the feeling of a complete scene or performance. I had to be at my best on every take — I couldn’t have a letdown.”

Despite the on-set struggles, Murray never regretted appearing in his first big film with Monroe.

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“I never really held it against her, because for her to agree to let me play this leading role was such a generous thing; she and I had never done a movie,” said Murray. “I was always aware of that and grateful to her.”

This isn’t the first time Murray has revealed what it was really like working with the famous blonde bombshell.

Back in 2014, Murray told FilmTalk.org that despite Monroe being a big star, she was plagued with insecurities.

“She was very insecure, very frightened of acting in front of the camera, which is amazing,” said Murray at the time. “… Being such a big star, she had done so many films, and yet, she was so frightened. But she took the part very seriously, listened to Josh Logan and took his directions. Her coach Paul Strasberg was also on the set: she was coaching her to do the role. A lot of directors had trouble with Paula being on the set, but for Josh, it worked fine. I think together with Paula, he created a wonderful character.”

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Despite Monroe’s personal struggles, Murray stressed Monroe wanted more than anything to be taken seriously as an actress and not just be recognized as a dumb blonde.

Marilyn Monroe is all smiles as she poses with fans in front of the Wilshire Beauty Shop at the premiere of director Jean Negulesco's film "How to Marry a Millionaire" in 1953. (Getty)

“I thought she was magnificent in it, although she was always late on the set and she had a hard time remembering her lines,” admitted Murray. “She also had a very short concentration span: She would start a scene and stop in the middle because she forgot her lines. So she had to do all of her scenes in tiny, little pieces because she couldn’t sustain a scene all the way through. We never saw a complete scene with her.”

Murray, along with his other castmates, felt “Bus Stop" would be a risk of becoming a box office failure due to the strenuous work it took for Monroe to play her part. They were stunned when they saw “Bus Stop" for the first time.

“… The first time we saw it at a preview, all of a sudden we realized what the magic of films was, with the editing and cutting it all together: she was magnificent!” said Murray. “I never understood why she was not nominated [for an Academy Award] for ‘Bus Stop.’ It was won by Ingrid Bergman – a wonderful actress, there’s no question about that – but Marilyn’s performance in ‘Bus Stop’ was so much richer, it had so much more variety and it was so much more interesting than Ingrid Bergman’s character in ‘Anastasia.’"

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Monroe passed away in 1962 at age 36 from a barbiturate overdose.