Mediate earned his fifth career win on the PGA Tour and first since the 2000 Buick Open. The victory was his second at the Greater Greensboro Classic, making him the eighth multiple champion of the event.
Tiger Woods held on to his top-ranked position, followed by Phil Mickelson, Ernie Els, Retief Goosen and Sergio Garcia, who won the Canarias Open de Espana last week on the European Tour.
Garcia managed a one-over 73 in the final round but held on for a four-shot victory, his first as a professional in his native Spain.
David Duval remained in sixth while Vijay Singh was seventh. David Toms, who will defend his title at the Compaq Classic of New Orleans this week, stayed put at No. 8, followed by Davis Love III.
European Ryder Cup player Padraig Harrington exchanged positions with Chris DiMarco to round out the top 10.
Mike Weir dropped one spot to 13th to accommodate Mediate's move. The Canadian was followed by European Ryder Cup member Darren Clarke and Jose Maria Olazabal.
Bernhard Langer fell one position to 16th while Scott Verplank, one of Curtis Strange's captain's picks for the U.S. Ryder Cup squad, also dropped one spot to come in at No. 17.
Jim Furyk, who finished tied for 23rd at the Greater Greensboro Classic, fell back to 18th in the rankings.
Kenny Perry remained at No. 19 followed by Bob Estes, who stayed put to round out the top 20.
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