Taylor Swift surprises fans and performs with Selena Gomez on stage

Taylor Swift emotionally thanked Selena Gomez for being there 'no matter what' after the pair performed a surprise duet together over the weekend.

They sang Gomez's sexy hit 'Hands to Myself' in front of a 60,000-strong audience at Swift's concert in Pasadena, California.

In an Instagram Story post that showed behind-the-scenes rehearsal, the pals lovingly gushed about each other.

"We're gonna sing 'Hands to Myself' which is an absolutely iconic bop," Swift said.

"Yes, Taylor loves that one, and I love her for loving it," Gomez said.

"It's my favourite song," Swift said.

Before the pair shared a warm embrace onstage, Gomez took the opportunity to tell the audience why she loves Swift so much.

"She's been my best friend for 12 years, almost 13. And the reason she has stayed one of my best friends is because this person has never judged a single decision I've made," said the 'Come & Get It' hitmaker.

"She's also met me where I've been. She's encouraged me when I have nothing to be encouraged about. I don't know if I'd be as strong as I am if I didn't have you and your family, because you've changed my life."

Swift is currently on her Reputation world tour, which comes to New Zealand in November.

Newshub.