could be coming back to Green Bay straight DIESEL ... 'cause it looks like the Pro Bowler has taken up P90x creator Tony Horton's offer to train him ... we think.
We broke the story ... Horton made an on-camera plea to Lacy -- basically begging to train the running back -- after Packers head coach Mike McCarthy demanded Lacy drop 30 pounds before next season.
Well there is some evidence to suggest the two have linked up and are getting it RIGHT NOW in Jackson Hole, Wyoming .