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Ariana Grande, Stand Up To Cancer

ABC/Kevin Mazur

Stand Up to Cancer didn't have one problem with Ariana Grande.

After reports surfaced Saturday morning that "The Way" singer was "a total nightmare" backstage, the show's executive producer and director is speaking out to refute the accusations.

"The U.K. Daily Star's story on Ariana Grande is completely false," Joel Gallen tells E! News exclusively. "Ariana was wonderful to work with, very gracious and a consummate professional to our team and everyone at the Stand Up to Cancer telecast."

He added, "Her moving performance of ‘My Everything,' which she sang in honor of her grandfather who passed away from cancer, was one of the most emotional moments of the night. We were honored to have her join us."

The pop star's grandfather lost his battle with cancer July 22. At the time, Grande shared how difficult the loss was for her.

"We did lose my favorite person to ever exist yesterday, my grandpa. If only y'all knew how amazing he was," she Tweeted. "My [heart] hurts so much…This is the hardest thing imaginable but I'm so grateful that I got to spend time with him & my family."

The grief she experienced propelled her to perform at Friday's telecast, which was broadcast on 36 U.S. networks, as well as in Canada and overseas.

"Supporting a cause that is near & dear to my heart," she Tweeted before showtime. "tonight I'm singing for grandps! I miss u."

Gwyneth Paltrow, Katie Couric, Reese Witherspoon, Jon Hamm, Joe Manganiello and Jennifer Hudson were just some of the stars on hand to support Friday's telecast at the Dolby Theatre in Hollywood.

Before Friday's show, more than $261 million had been pledged to support various innovative cancer research programs. 

You can still make a difference by donating through the official website