Mickelson, who has been ranked as high as second, improved four spots as he won in his 2004 PGA Tour debut.
Tiger Woods, who will make his next appearance on the PGA Tour at the Buick Invitational in February, stayed put atop the rankings. Vijay Singh, who will look to defend his title this week at the FBR Open, followed at No. 2.
Third-ranked Ernie Els is in Thailand to defend his title at the Johnnie Walker Classic this week. He held his position from last week as did Davis Love III, Jim Furyk, Mike Weir and Retief Goosen, who ranked from No. 4 to No. 7, respectively.
Kenny Perry exchanged places with David Toms to come in at No. 8 this week, while Toms dropped to No. 9. Padraig Harrington rounded out the top-10 as Europe's top-ranked golfer.
Stuart Appleby remained unchanged at No. 11 followed by Mickelson. Darren Clarke, Nick Price, Chad Campbell and Robert Allenby each dropped one spot to accommodate Mickelson's move up the rankings.
Fredrik Jacobson held onto the 17th spot, while Jay Haas improved eight positions to No. 18 following another solid performance at the Bob Hope. Justin Leonard stayed put at No. 19 followed by Charles Howell III, who fell two spots to No. 20.
Marcel Siem survived a three-way playoff on Sunday at the dunhill championship to earn his first career victory on the European Tour. The 23-year-old improved 121 positions in the rankings to come in at No. 190 this week.