Kelly posted a two-shot victory over Davis Love III and joined Tiger Woods, Phil Mickelson and Len Mattiace as the only multiple champions on the PGA Tour in 2002.
Woods held on to the top spot for the 151st consecutive week. His preparation now is for the British Open at Muirfield, where he looks to grab the third leg of the Grand Slam after winning both the Masters and the U.S. Open.
Phil Mickelson took second this week, followed by Ernie Els and Retief Goosen, who shared second place at the European Open Sunday and will defend his Scottish Open title at Loch Lomond this week.
Sergio Garcia came in fifth and reigning PGA Champion David Toms remained in sixth place.
Love, who finished as runner-up for the second consecutive year at the Western Open, jumped two places to seventh while 2001 British Open champion David Duval fell one to No. 8.
Vijay Singh dipped one rung to ninth while Irishman Padraig Harrington, who also tied for second at the European Open, rose two places to round out the top 10.
Jim Furyk and Nick Price each fell one spot to 11th and 12th, respectively.
Chris DiMarco, Darren Clarke and Bob Estes held their rankings from last week to complete the top 15.
Michael Campbell of New Zealand bogeyed his final four holes Sunday but it was still enough to win the European Open, his fifth title on the European Tour. He climbed 13 spots to No. 16 in this week's rankings.
Angel Cabrera, Colin Montgomerie, Rocco Mediate and Kenny Perry each dropped one spot because of Campbell rise into the top 20. Canada's Mike Weir fell out of the top 20.
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