There was plenty of change to the top 20 this week behind world Nos. 1 and 2 Tiger Woods and Phil Mickelson.
Adam Scott and Ernie Els held steady in the fourth and fifth positions behind Harrington. Geoff Ogilvy tumbled three notches to six and was followed by Sergio Garcia, who remained seventh this week.
Stewart Cink was down two to eight, while Steve Stricker dipped one to No. 9 and Jim Furyk rose two to 10th.
Henrik Stenson soared six places to 11 this week. The next four players all fell in the rankings -- Justin Rose was down three to 12, K.J. Choi slid a pair to 13, Anthony Kim dipped one to 14 and Vijay Singh tumbled five spots to 15.
Kenny Perry held steady in 16th, while Trevor Immelman slipped two to 17th. Lee Westwood and Rory Sabbatini exchanges places with Westwood up to 18th. Miguel Angel Jimenez closed out the top 20 again this week.
Ian Poulter, who took second behind Harrington, jumped 19 positions to 23rd this week.