NMinajBrit230.jpgNicki Minaj is opening for Britney Spears on her Femme Fatale world tour, and Minaj is happy the experience will be completely substance-free "as it should be," she tells Life & Style.

    "I think it's a great thing. If that's the way Britney wants it, so be it. She's the queen of her castle. It trickles down and makes everyone responsible."

Minaj says touring with Britney will be life changing.

    "We start on June 17, and I'm sure it's going to be a whirlwind. I'm sure it's going to change the way I view touring. Every tour I do is different, and I get new energy."

Britney has been in the press as of late because her ex-manager Sam Lutfi is filing a motion to get her a court-mandated psychiatric evaluation.

Lutfi argues that Spears is mentally capable to testify in his lawsuit against her mother, Lynne, for allegedly defaming him in her memoir, Through the Storm. Lynne and Britney's father, Jamie, say their daughter is too mentally unstable to testify. Lutfi says that if Britney can go on tour, she can testify in court.