Jonathan Grella, a 33-year-old who works in public relations in Washington, D.C., and was once a spokesman for former House majority leader Tom DeLay, says that as he’s gotten more successful, he’s sometimes wondered if his mentors see him as a competitor. “They may counsel you to ask for that big raise, but they don’t want you to make as much as they did at your age, and certainly not as much as they make now,” he says.

So if your office mentor isn’t stepping aside and allowing you to ascend the throne, you’ll have to take matters into your own hands. Just handle the process delicately, or it could end up messier than your breakup with the high-school girlfriend you outgrew.

Lay the groundwork for the split the way you would in any relationship. Taper off your interactions with your workplace father figure. If you used to meet for lunch, have coffee instead. If you used to talk with him in person, switch to phone calls or e-mails. “Keep yourself from asking for advice,” says Sharon Griggs, who’s on the board of directors of the California-based Professional Coaches and Mentors Association. “If they continue to offer it, say ‘I appreciate your advice on the subject, but I’ve come up with my own strategy on this.’ You want to change the balance of power.”

“Do as little as possible that’s gratuitously damaging,” says Ellen Ensher, the author of Power Mentoring: How Successful Mentors and Protégés Get the Most Out of Their Relationships. “Industries are small. You never know where this person may pop up again.” For example: When Brett Ratner defied a former mentor, New Line Cinema CEO Bob Shaye, and went overbudget making Rush Hour 3, Shaye called the wasted money “a betrayal of the trust New Line has put in him.” There are no immediate plans for Rush Hour 4.

Still, the risk of inciting retaliation almost never outweighs the risk of staying in a relationship that’s dragging your career down.

In 2003, a 36-year-old adviser to a high-profile Wall Street figure watched his mentor get fired during a controversy over his compensation. Then he lost his job too. “Living in someone else’s shadow can be comfy for a while,” he says. “But complacency is the great destroyer of careers.”