LONDON: RIHANNA stunned fans at her London album launch by bringing mentor JAY-Z on stage - just weeks after she guested at his Los Angeles show.

The singer performed a 40 minute set in London on Monday night (16Nov09), singing a string of classic hits as well as five tracks from her forthcoming album, Rated R.

But the beauty saved the highlight of the show until the end - introducing Jay-Z to the ecstatic crowd, who went wild as the pair sang their hit track Run This Town together.

Rihanna joined her mentor during his show at the University of California earlier this month (08Nov09).

Jay-Z's appearance at the launch marks his second surprise gig in as many days in the U.K. capital - he took to the stage at his wife Beyonce's concert on Sunday (15Nov09).