Australian Scott led by two overnight and the 30 year old reached the turn in a respectable two under par 34, but Poulter halved the deficit with an eagle at the par five fourth helping him play the front nine in just 33.
And it was all change at the top when Poulter sunk a 20 foot birdie putt at the tenth and Scott missed from five feet for par.
World Golf Championships-Accenture Match Play winner Poulter then made an impressive clutch putt of his own at the 12th to retain the advantage and stay 14 under par.
US Open Champion Graeme McDowell was in third, the Northern Irishman holing a 50 foot putt at the 14th to reach three under for the day and 12 under for the week.
Anders Hansen had set the clubhouse benchmark at 11 under after a superb round of 65, and was joined by Korean Kyung-nam Kang and Dutchman Joost Luiten - both of whom were still playing the back nine.