Eminem and Rihanna turned the rapper's Lollapalooza set into a mini-rehearsal for their upcoming joint tour on Friday night (01Aug14) when the Umbrella hitmaker joined her pal onstage in Chicago, Illinois.

Six days before the pair launch the Monster tour at the Rose Bowl in Pasadena, California, Eminem introduced Rihanna as a surprise guest during his Lollapalooza festival headlining set in Grant Park.

They serenaded fans with their collaborations Love The Way You Lie and The Monster, and Rihanna also thrilled by performing Dido's part to the rapper's 1999 hit, Stan.

Eminem's hits-laced set ended on a sombre note as he performed Lose Yourself, his signature tune from the movie 8 Mile, as images of his native, bankrupt Detroit, Michigan burning flashed on a screen behind him.