Casey needed a closing 65 Sunday to fend off two players to earn the title at the Abu Dhabi Golf Championship.
Ahead of Casey, there was no change in the top-12 spots in the rankings. Tiger Woods, who will make his PGA TOUR debut this week, remained atop the rankings.
Woods was followed by Jim Furyk, Adam Scott, Phil Mickelson, Ernie Els, Vijay Singh, Luke Donald, Retief Goosen, Padraig Harrington, Geoff Ogilvy, Sergio Garcia and Trevor Immelman.
Casey moved up just one spot to 13, bumping Henrik Stenson to 14. David Howell and Davis Love III held steady in the next two places.
David Toms knocked Colin Montgomerie down a space, with the American moving to 17th and the Scotsman slipping to 18. Jose Maria Olazabal stayed put at 19, while Chris DiMarco was up one to 20th. To make room for DiMarco, Nick O'Hern dipped a notch to 21.
Charley Hoffman claimed his first PGA TOUR crown at the Bob Hope Chrysler Classic on Sunday. The win vaulted him 105 places to 92nd in the world.