Thomas Mars of Phoenix performed during the Coachella Music Festival in Indio, Calif., Saturday. Reuters/Mario Anzuoni

Phoenix had a surprise for Coachella and the thousands of fans in the crowd as R. Kelly came out and performed a slowed-down version of “Ignition (Remix)” to end the main part of the set.

Phoenix, fronted by Thomas Mars, headlined Coachella on Saturday one night after the Stone Roses and Blur did the same at the Indio, Calif., music festival.

Phoenix is known to throw in a few surprises during its biggest performances. When the band sold out New York City's Madison Square Garden in 2010, it brought out Daft Punk during the encore as a way to celebrate such a big show. Laurent Brancowitz, Phoenix’s guitarist, was previously in a band with Daft Punk's Thomas Bangalter and Guy-Manuel de Homem-Christo.

At Coachella, R. Kelly ended Phoenix’s main set with his version of “Ignition (Remix).” He started singing a cappella before the first chords of Phoenix’s “1901” could be heard and then went into “Ignition (Remix)” with the band playing as support. R. Kelly soon transitioned to “I’m a Flirt,” from 2007’s “Double Up” album before going back to “Ignition (Remix),” with Mars providing backing vocals.

It has been a long time since Phoenix acted as a backing band, having played behind Air during several television performances in 1999. Phoenix will be releasing new album "Bankrupt!" on April 23.

View the R. Kelly and Phoenix collaboration at Coachella below.