KATHERINE HEIGL is distancing herself from her meddling mom in a desperate attempt to save her Hollywood career, says an insider.

The former “Grey’s Anatomy” star landed the lead role in a yet-unnamed NBC drama after a string of movie flops and bad press – but she’s so worried about her diva reputation that she banned her high-powered “momager” Nancy from the set.

“Katherine knows her new TV show is her last chance to prove she’s not too difficult to employ,” revealed a close source. “She’s very concerned that her mom has hurt her career, so she told her it would be best if she kept her distance from the production.

“Katherine is telling pals she’s seriously considering ditching her mom and hiring new management.

“But she’s so scared of incurring Nancy’s legendary wrath that she’d still let her keep her manager title in name only.”

As The ENQUIRER recently reported, the 34-year-old Emmy winner damaged her once-flourishing career with outrageous demands and difficult behavior.

The beauty first made waves in 2007 when she threatened to quit “Grey’s Anatomy” while negotiating a pay raise. She eventually left in a snit for big-buck film roles.

But a string of duds followed, and the star was reduced to doing sleep-aid TV commercials. Now thrilled by the opportunity to play a CIA analyst on TV, Heigl is apparently taking no chances that her mom will screw things up for her.

Said the source: “Katherine is adamant that her mom make herself scarce so she can pour on the charm and stay in the network’s good graces.”

Meanwhile, a rep for Heigl denied she is distancing herself from her mother.