Defending champions Sean O'Hair and Kenny Perry share top spot after round one of the Franklin Templeton Shootout in Naples, Florida.
The duo took the crown by a single shot last year and all the indications were that it will be a tight contest this time around with three pairs sharing top spot on eight under.
Charles Howell finished second last year alongside Rory Sabbatini and he held a share of lead playing with new partner Justin Leonard.
Fellow American duo Matt Kuchar and Harris English also fired an eight under par round and shared a spot at the summit, three shots clear of the rest of the field.
Retief Goosen and Freddie Jacobson, playing in place of Boo Weekley who withdrew following family bereavements, were the nearest challengers.
US PGA champion Jason Dufner and Dustin Johnson were a further shot back alongside Chris DiMarco and Billy Horschel followed by Sabbatini and Scott Verplank on three under.
European Ryder Cup pair Ian Poulter and Lee Westwood recovered from a slow start to finish on two under while another couple of Americans, Jerry Kelly and Steve Stricker, were one shot better than par.
Tournament host Greg Norman was playing with Swede Jonas Blixt and they were level alongside Mark Calcavecchia and Chad Campbell.
Former Masters champion Mike Weir and South African Graham DeLaet were bringing up the rear after Friday's round of modified foursomes, with fourballs to follow on Friday and a final round scramble format on Sunday.