Eminem surprised Lollapalooza attendees on Friday, Aug. 1, when Rihanna appeared on stage and joined him for three songs: 'Love the Way You Lie,' 'The Monster' and 'Stan.'

While Rihanna did lend her vocals to the album versions of 'Love the Way You Lie' and 'The Monster,' Eminem's 1999 song 'Stan' was originally recorded by Dido.

Lollapalooza is being held this weekend in Chicago's Grant Park. and boasts an all-star lineup including Iggy Azalea, Zedd and Lorde.

Both Eminem and Rihanna will be hitting the road soon for The Monster Tour, which includes stops in Pasadena, Calif.; East Rutherford, N.J.; and Detroit, Mich. in August. The Monster Tour will be Eminem's first U.S. tour since The Recovery Tour in 2011.

Earlier in the week, Rihanna shared a photo with Slim Shady rehearsing for the tour.

Click on the videos below to check out fan recordings of Eminem and Rihanna on stage together.

Eminem and Rihanna Perform 'Stan'

Eminem and Rihanna Perform 'The Monster'

Eminem and Rihanna Perform 'Love the Way You Lie'

Rihanna + Other Celebrity Yearbook Photos

More From 93.1 KISS FM