Christina Aguilera wants to lose 40lbs in four months.
The 33-year-old singer only gave birth to her daughter Summer Rain two weeks ago but she's reportedly already thinking about getting her pre-baby figure back.
A source said: "She thinks there's no time to lose. Her target is to have her pre-pregnancy body back in time for her birthday on December 18."
The blonde beauty will have to wait another four weeks before she can participate in exercise as she delivered Summer via Caesarean section.
However, the 'Candyman' hitmaker has wasted no time kick-starting her high-protein diet and is allegedly keen to be ready to pose for Playboy magazine next year.
The source added to the US' OK! magazine: "Stripping down is totally her style."
The 'Voice' USA mentor bared her baby bump in V magazine before she and her fiancé Matthew Rutler welcomed their little girl into the world, and she admitted she was very "proud" of her changing figure.
She said at the time: "As a woman, I'm proud to embrace my body through all stages of life, staying fearless and confident in surrendering to the unknowns the future has in store."
Christina also has six-year-old son Max with ex-husband Jordan Bratman, whom she divorced in 2011.