It's official, tennis hottie
Anna Kournikova has signed a deal to join "
The Biggest Loser" next season -- while THREE current stars of the show will be on their way out.

Producers confirm the 29-year-old will join the show as a celebrity trainer ... but trainers
Jillian Michaels,
Brett Hoebel and
Cara Castronuova will not return for Season 12.
Exec. producer Todd Lubin tells New York Magazine the decision to hire Anna was all part of an effort to reboot the show for it's 12th season.
We're "getting slightly away from just the tape measure, and getting into overall well being and health. That's where Loser needs to go" explains Lubin.
He continues ... "She grew up with very little in Moscow, pounding tennis balls every day when she was 5. That's the drive she's bringing to the show."
Anna Kournikova's mother has officially been charged with one felony count of neglect of a child.
The Palm Beach County District Attorney's Office filed charges yesterday afternoon.
Alla Kournikova was arrested last month after her 5-year-old son Allan -- who is Anna's half-brother -- was injured after Alla allegedly left him home alone while she ran errands.
Allan was found crying and bleeding by the Kournikovas' neighbors, after he either jumped or fell out of a second story window. Allan was hospitalized with minor injuries.
If convicted Alla faces a maximum of 5 years in prison.
TMZ has obtained the 911 call made last week when
Anna Kournikova's mother, Alla, was arrested and charged with
child neglect.

As TMZ previously reported, Alla's five-year-old son -- who is Anna's half-brother -- fell out of a window after allegedly being left home alone. In the 911 call, you can hear the kid say he jumped.
One day after being arrested for child neglect
, Anna Kournikova's mother Alla was spotted outside her Palm Beach home toting a purse.

Alla's five-year-old son -- who is Anna's half-brother -- fell out of a window on Tuesday after allegedly being left home alone.
Anna Kournikova's
mother was arrested today and charged with
child neglect -- because her son was injured after he was allegedly left home alone.

The alleged incident involves Anna's 5-year-old half brother, Allan, who fell or jumped out of a second story window earlier today.
According to
WPTV.com, Allan landed on some rocks and then walked to the sidewalk. Neighbors found him crying, screaming and bleeding.
TMZ has
obtained police docs, which say the mother --
Alla Kournikova -- left Allan home alone, with all the doors "locked with a deadbolt." The police affidavit states Alla told cops she had left to run errands for around 50 minutes and Allan -- who was watching TV when she left -- did not want to go with her.
After cops arrived Allan told them he jumped from the window.
Allan has been hospitalized.
Story developing ...
Don't expect the sure-to-be freakishly perfect offspring of
Enrique Iglesias and
Anna Kournikova to take over the world anytime soon -- Iglesias says he's not "mature" enough to be a papa.

Enrique, who recently admitted to smoking pot for inspiration, is now 34 ... going on 13.
Tennis babe Anna Kournikova appears to have gained a pound, showing off her emaciated frame at the opening ceremonies of the
World Team Tennis Pro League in Sacramento on Thursday. Fault!

Even though she's never won a Grand Slam match, Enrique Iglesias' 26-year-old wife/girlfriend/whatever could still use a bowl or two of Wheaties -- the breakfast of, er, champions.

With her professional tennis career over, Anna Kournikova now spends her days drawing attention to serious world issues ... like breakfast!
Since the 25-year-old has always been better known for her killer body than for her killer tennis game, Anna can attest to how pivotal the day's most important meal is for maintaining a healthy physique. Special K, anyone?
Anna, seen here strolling Miami with alleged hubby Enrique Iglesias on Tuesday, is now the spokesperson for the Federal School Breakfast program's
"got breakfast?" campaign. This makes perfect sense, considering what a hot dish she is!
The stars came out last night for the fourth installment of 'Runway For Life,' benefiting St. Jude Children's Research Hospital. The celebrity fashion show celebrates the release of the Platinum Edition two-disc DVD of Disney's animated classic "The Little Mermaid." Proceeds from the DVD's sale will benefit the hospital.
Celebrities like Cindy Crawford,
Anna Kournikova, Cybill Shepherd,
Lisa Rinna and even Chris Klein all walked down a virtual underwater catwalk dancing to the sounds of the Disney feature.
Our cameras were rolling all night, catching all the action that went down on the red carpet, inside the show and under the sea