Tiffany wasn’t alone during a performance that ended on a sour note.

On Sunday, the ‘80s pop star was in Melbourne, Florida, for a show where she lost her cool. In a video obtained by TMZ on Monday, the 50-year-old was seen struggling as she attempted to belt out her hit single "I Think We’re Alone Now." Tiffany, whose real name is Tiffany Darwish, was heard singing hoarsely and even skipped some lyrics at some points.

In response, a spokesperson for the singer told Fox News that "Tiffany lost her voice and was frustrated with her performance."

While some fans in the video were seen supporting Tiffany by singing along, toward the end of the track, the singer may have witnessed someone from the crowd heckling, which prompted her to say, "F—k you, guys."

TIFFANY REFLECTS ON ‘80S HIT ‘I THINK WE’RE ALONE NOW,’ ALLEGED RIVALRY WITH DEBBIE GIBSON

"This is my hit!" she yelled while barefoot. "I’m gonna sing it right!"

The video has since gone viral, prompting fans to express concern on social media.

"Poor woman," one person commented on YouTube. "She’s trashed. Her fans are loyally singing with her. Oh well we all have our days."

"As the malls around the country disappear, so does Tiffany’s talent," one user slammed the singer. "They’re forever tied together."

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"This saddens me immensely," another chimed in. "When I think of her.. and the happy times that surrounded hearing her music in the day… I wish I hadn’t view [sic] this… Hope things turn back around for her."

"I Think We’re Alone Now," which is a cover of the Tommy James & the Shondells song, was Tiffany’s biggest hit. It was released in 1987.

In 2019, she was headlining a U.S. tour after performing 55 shows in 53 cities for the "Mixtape Tour" alongside Debbie Gibson.

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Singer Tiffany

Tiffany performs during the 2021 Kentuckiana Pride Festival at Big Four Lawn at Louisville Waterfront Park on Oct. 08, 2021, in Louisville, Kentucky.  (Photo by Stephen J. Cohen/Getty Images)

"I never get tired of performing ‘I Think We're Alone Now,’" she told Fox News at the time. "I was an 8-year-old girl twirling around in her bedroom in Norwalk, California, wanting to be a singer. And it happened. And ‘I Think We're Alone Now’ led me to success around the world."

"It was bigger than I even imagined, even when I got the record deal," she continued. "It was one thing to be a singer in America, but then when I started to travel the world and everyone loved the song and were wearing jean jackets, knew a lot about me as a person — it really affected me. I never get tired of singing that song because it makes people happy."