Britney Spears Opens Up About Grueling Rehearsals For Femme Fatale Tour

Britney Spears is beyond excited to hit the road with Nicki Minaj for her upcoming Femme Fatale tour.

The pop star tells ET:

"I'm probably going to be extra nervous the day before. We've been working hard for, like, two months now and everything's coming together really good."

As for her hardcore rehearsals, Brit adds:

"It can be kind of [grueling], especially when you're on stage and you're on your eighth number. You get really winded and you're like, 'How can I do the rest of the show?' But I've been training for a while and I actually - before I come to rehearsals - I've been working out and stuff like that so I won't have that predicament."

The mama of two, who says regular runs help maintain her weight, also reveals that she can't go anywhere without her favorite pillow. See the interview ... after the jump.