Demi Lovato has been listening to Nicki Minaj's "grimy" music to get her in the mood for her MTV Video Music Awards (VMAs) performance.

The 20-year-old songstress is singing at tonight's red carpet pre-show. Demi likes to listen to certain music to calm her nerves before performing.

"What really pumps me up is 2 Chainz and Nicki Minaj, but not her pop stuff. Like, you know, the grimy stuff," she smiled in an interview with MTV News.

The star also revealed she's "making sure that I'm well-rested so I don't look like a hag when I step out on stage to perform."

Demi has performed live numerous times before, but admits that doesn't make it any easier. The brunette star says being surrounded by her favourite stars when she's on the stage has added another dimension to her show.

"I'm really nervous to perform because there's going to be a lot of celebrities walking the red carpet at the same time that I come out and perform, so not only do I want to do a good job because it's on camera, but also there's people that I really admire on the red carpet," she explained.

"It's kind of nerve-racking."