Fifth Harmony has a sixth member… at least for a night.

During the latest stop on her 1989 tour at Levi’s Stadium in Santa Clara, California, Taylor Swift invited the all-girl group, comprised of Camila Cabello, Ally Brooke Hernandez, Lauren Jauregui, Normani Hamilton and Dinah-Jane Hansen, on stage to perform their hit single “Worth It.”

“Scream louder for them than you’ve screamed for me the entire night,” Swift told the hyped-up crowd when introducing Fifth Harmony.

Swift also prefaced the high octane performance by informing the crowd that her shiny blue outfit had been loaned to her by a friend.

“[She’s] in one of the biggest and most successful groups in the world. They have one of the most powerful and loyal fanbases in the world,” said Swift. “They also have one of the biggest smash hit singles in the country right now called ‘Worth It.'”

The stadium went crazy. Swift fit right in with the Fifth Harmony girls, strutting her stuff throughout the performance.

“Worth It” is the group’s third single from their debut album, Reflection, and Fifth Harmony’s first single to sell more than a million downloads.