EXCLUSIVE

Eddie Lacy is no dummy ... and knows if one of the biggest fitness gurus in the country offers to whip your butt in shape -- you listen.

TMZ Sports has learned ... Lacy's people have been in touch with P90X creator Tony Horton -- after Tony offered to PERSONALLY train the Green Bay Packers running back.

Horton -- who's trained all sorts of huge stars, athletes (Ray Lewis) and even politicians (Paul Ryan) -- previously told TMZ Sports he already has a game plan to help Lacy drop his extra weight and get into the best of shape of his life before next season.

Now, Lacy's people have confirmed the two sides have touched base in the hopes of working something out ... though no agreement has been struck yet.

Horton says he doesn't want to undermine Green Bay's training plan for Lacy -- but instead, he wants to work WITH the team to get Eddie where he needs to be.

"The Packers will get him ready for the season. My job will be to get the weight off and help him eat better."