Estes earned his fourth career title on the PGA Tour with a one-shot victory over Rich Beem at the TPC at Avenel in Potomac, Md. The win was his first of the 2002 campaign and his third in the last 12 months.
Tiger Woods remained perched atop the rankings with the No. 1 spot. He was followed by Phil Mickelson, Ernie Els and Retief Goosen, who will defend his U.S. Open title at Bethpage State Park's Black Course in Farmingdale, N.Y., next week.
Sergio Garcia, who will attempt to become only the second player to win back-to-back Buick Classics this week, stayed put at No. 5. David Toms exchanged positions with David Duval to come in at No. 6 while the 2001 British Open winner dropped to seventh.
Vijay Singh held on to the eighth position followed by 2002 Memorial champion Jim Furyk and Chris DiMarco.
Nick Price remained in 11th while Padraig Harrington and Davis Love III kept their places at 12th and 13th, respectively.
Angel Cabrera dropped one spot to 15th to accommodate Estes's move up the rankings. Colin Montgomerie moved up one position to No. 16 while Rocco Mediate fell two rungs to come in at No. 17.
Darren Clarke also dropped two places to No. 18. He was followed by Kenny Perry and Mike Weir.
England's Justin Rose, who earned his second career win on the European Tour at the British Masters on Sunday, jumped 21 spots to come in at No. 48.
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