Rihanna thrilled fans at her concert last night at the Izod Center in East Rutherford, New Jersey by bringing out her mentor and frequent duet partner, Jay-Z.

As Rihanna sang the intro to 'Run This Town,' she threw up a diamond and the rapper popped up through a hole the stage, surrounded by a cloud of smoke. He stood almost motionless for a full minute, basking in the applause as the audience went nuts.

The pair performed 'Run This Town,' their collaboration with Kanye West, who just happened to show up at a Rihanna concert two days ago to perform the very same song. Jay stayed around to deliver his opening verse on the Grammy-winning smash hit, 'Umbrella,' before calling it a night.

A multiple nominee at this year's MTV Video Music Awards, Rihanna continues her Loud Tour this weekend with shows in Philadelphia in Boston.

Watch Jay-Z and Rihanna Perform 'Run This Town' Together