Taylor Swift & Nelly Performs 'Dilemma' At Karlie Kloss' Birthday In The Hamptons (VIDEO)

ST LOUIS, MO - SEPTEMBER 29: Taylor Swift performs with HAIM and special guest Nelly onstage during the 1989 World Tour at Scottrade Center on September 29, 2015 in St Louis, Missouri. (Photo by Dilip Vishwanat/LP5/Getty Images for TAS) *** Local Caption *** Taylor Swift;Nelly;HAIM

Taylor Swift and Nelly reunited at Karlie Kloss' birthday party in the Hamptons on Saturday night (August 6) for a playful performance of the rapper's 2002 duet with Kelly Rowland, "Dilemma."

Even though E! reported that Taylor initially didn't want to perform, Nelly apparently asked the pop titan to fill Rowland's shoes and she obliged. But is it that much of a surprise? They do have history of collaborative performances, including “Just a Dream” in 2011, “Hey Porsche” in 2013 and “Hot in Herre” in 2015. Both were on-site to celebrate the supermodel's 24-year-old birthday.

"Taylor was in an amazing mood, and super fun all night," an insider told the outlet. "She danced her ass off. At first she didn't want to perform but then Nelly asked her. Everyone was super into it, the crowd loved it."

Photo: Getty Images