Lil Uzi Vert held his annual Lil Uzi Vert + Friends holiday concert in Philadelphia on Saturday night (Dec. 8). Among the many surprise performances during the show was a special appearance from Chicago rapper Chief Keef.

Uzi and Keef performed a new song called “Rollie” at the show. Over a bouncy, bass-heavy beat, Uzi and Keef spit luxury bars about their rich lifestyles.

In one line, Keef is heard rapping, “Cup out for Henny/I feel the envy.” Meanwhile, Uzi is doing his trademark dance moves while the crowd is joyously bouncing up and down. Uzi has always cited Keef as a major influence on his music, so seeing the rap duo perform together on stage was a special moment for the City of Brotherly Love.

There’s no word if this new track will appear on Uzi’s upcoming album, Eternal Atake. Fans have been patiently waiting for the former XXL Freshman to release his project.

At his Philly show, Uzi also delivered another update on the album. "I know y'all wonder when I'm gonna drop my album," he told the crowd. "I'm finally done with that joint, I'ma drop that joint," he added without providing a concrete release date.

The 24-year-old rapper has been teasing the album since July when he released the controversial LP artwork, which has gotten him in legal trouble with the religious cult Heaven's Gate. Uzi also released the single "New Patek," which recently went gold.

Check out Lil Uzi and Chief Keef performing "Rollie" at their Philly concert below.

See Behind-the-Scenes Photos of Lil Uzi Vert at the 2016 XXL Freshman Shoot