Calcavecchia finished at 10-under 274 for his 13th PGA TOUR victory and first since the '05 Canadian Open. He ended one shot ahead of Slocum and John Senden.
This year, just seven players ranked inside the world top 25 will be in the field: No. 3 Ernie Els, No. 4 Steve Stricker, No. 7 Justin Rose, No. 16 Stewart Cink, No. 17 Geoff Ogilvy, No. 21 Trevor Immelman, No. 23 Scott Verplank.
Els is coming off a win at the Honda Classic last week, his first victory on the PGA TOUR since the 2004 WGC-American Express Championship and his 16th overall. He moved up from No. 4 in the world rankings last week to third.
Calcavecchia tied for fourth place ahead of his title defense this week.
The GOLF CHANNEL will have coverage of the first two rounds and NBC will broadcast the weekend.
Next week is the Arnold Palmer Invitational, where Vijay Singh won last year.