NBC has announced that Anna Kournikova will join The Biggest Loser as its celebrity personal trainer, replacing Jillian Michaels. 

The show which is entering its twelfth season is currently going through an overhaul. The show's executive producer, Todd Lubin, told Vulture 'that the Kournikova hire is part of a reboot that will see the show getting slightly away from just the tape measure, and getting into overall wellbeing and health. That's where Loser needs to go.' 

Replacing Jillian's tough way was not the intention of the show when selecting a new trainer. Kournikova had previously caught the interest of the producer when she made an appearance on the show in season ten. The athlete impressed Lubin by engaging the participants in a tennis themed workout. 

As for Kournikova's 'celebrity appeal' the show has acknowledge that she is well known, but that she is no diva. Lubin says the star is the furthest thing away from acting like a diva. 

She grew up with very little in Moscow, pounding tennis balls every day when she was 5, Lubin says. That's the drive she's bringing to the show.

But what's alarming about Anna is that when she really gets intense, she starts speaking Russian, he continued.

And as a child of the Cold War, it scares me when she does.

In a spot on for The Biggest Loser's twelfth season promo, Anna says, The mind is a powerful thing. You can make things happen if you want them bad enough.

I know all about discipline, strength, conditioning -- commitment . . . and now I'm going to teach the contestants everything I know.