Two sons of the late Alan Thicke, who played the beloved dad on the hit TV sitcom “Growing Pains,” on Tuesday fired a pre-emptive strike in what could become a nasty legal battle against the actor's third wife over his estate.

Robin and Brennan Thicke, co-trustees of their father's living trust, accused Tanya Callau of “avarice and overreaching” in claiming to them that the 2005 prenuptial agreement she signed was invalid and seeking a greater portion of their father's estate.

She also threatened to go to the tabloids with the story if they did not accede to her demands, according to the petition filed in Los Angeles Superior Court filed by Venable partner Alex Weingarten.