Jessica Simpson has tweeted Jessica Alba about her post-baby physique telling her it was a "job well done".

Simpson is just weeks away from giving birth to her first child with fianc Eric Johnson. She has evidently seen pictures of Alba on the beach in Mexico during her recent vacation where she looked amazing in her bikinis.

Alba welcomed her second daughter, Haven, just four months ago and is already sporting toned abs and a lean figure leading Simpson to send her a gushing message on the social networking site.

"New goal: look like Jessica Alba after baby," the 31-year-old reality star turned fashion mogul wrote. "Job well done, lady!"

Alba responded with a Twitter message and was obviously flattered by the comment.

"OMG! You're so sweet!" she wrote. "Thanks, hon!"

The Sin City star has revealed that she didn't go "too crazy" to lose the baby weight but that she learned lessons from when she gave birth to first child Honor three years ago.

"I didn't gain as much weight with my second pregnancy, so I think that made a really big difference," she told Us Weekly.

"I did prenatal yoga up until the very end. I just made healthier choices. I started working out and not going too crazy, but I did what was safe and doctor approved."

Jessica is reportedly negotiating a $4 million Weight Watchers deal to help lose the pounds after she gives birth.