The pop superstar has become known for inviting celebrity guests to join her onstage during her track Style, but this weekend's show in Tampa was a little different as she strutted out dressed as Olaf the snowman, while her dancers accompanied her as reindeers.

"I don't know if you noticed but we have a Frozen theme going on here," she said. Teasing the audience, she added, "If only Idina Menzel were here."

On cue, Idina rose up from a trap door, wearing a turquoise sequin gown to bring her animated character Princess Elsa to life. She then launched into her signature song, much to the crowd's delight, before the stars stripped off their costumes to complete the set in more typical stage attire.

"Frozen totally happened tonight," Taylor wrote on Instagram after the gig, alongside a photo of the pair. "And 55,000 people sang 'Let it Go' so loudly, it nearly took my breath away. Good times, @idinamenzel."

The Broadway veteran also gushed about the big moment on social media by sharing a video clip of their performance online. "Thank you @taylorswift!" she wrote. "That was definitely an out of body experience. Or out of Elsa's body experience!"

"@taylorswift13 deserves all her success and more," she added on "Generous, real, loving. Thanks Taylor for the gig of a lifetime."

Idina wasn't the only special guest at the show - Taylor also shared the stage with up-and-coming singer Alessia Cara, just months after she put her own spin on the superstar's Bad Blood hit on BBC radio. The cover caught the attention of Taylor, who brand the newcomer's version "amazing", and invited Alessia to perform for her Florida fans.

"Thank you for showing me what 55,000 people looks like," Alessia posted online after belting out her track Here. "You are the classiest, sweetest, most lovely person and I can't thank you enough for what just happened. Also I can't feel my body. Goodnight everyone I quit life."

The Tampa show marked the final North American date of Taylor's 1989 World Tour, which has previously featured appearances by the likes of Ricky Martin, Pitbull, Beck, John Legend, Alanis Morissette, The Weeknd, Chris Rock, Ciara, Lorde, Matt LeBlanc, Mary J. Blige, Julia Roberts, Mick Jagger and the stars of her Bad Blood video.

"Sharing a stage with @alessiacara and @idinamenzel was the perfect way to end this amazing chapter," she tweeted. "Thanks ladies."

The singer will next head to Singapore on 7 November (15) to continue her trek in Asia and Australia, where she will wrap up the gigs with a three-night run in Melbourne in December (15).