Rapid Grappler
You are a quick hand at grappling.
Prerequisite: Dex 13, Greater Grapple, Improved Grapple, Improved Unarmed Strike, base attack bonus +9 or monk level 9th.
Benefit: Whenever you use Greater Grapple to successfully maintain a grapple as a move action, you can then spend a swift action to make a grapple combat maneuver check.
Source: Ultimate Combat, p. 114