Taylor Swift performed in the Hamptons over the weekend, taking the stage Saturday night with Nelly for oil heir Mike Hess’ 30th birthday.

“I know you know that song,” Nelly told Swift before the pair launched into the rapper’s 2002 hit “Dilemma,” with Swift taking on Kelly Rowland’s part.

Swift has performed with Nelly before, bringing him onstage last year during a concert in St. Louis.

The “Shake it Off” singer’s squad member, model Karlie Kloss, who just turned 24, was also at the bash along with “Hamilton” star Leslie Odom Jr. and Heidi Klum.

Reportedly missing out on the action was Swift’s boyfriend Tom Hiddleston.

This article originally appeared in the New York Post's Page Six.