Steve Stricker and Sean O'Hair built on a swift start to produce a 15-under par 57 as they took a one-stroke lead after the opening round of the QBE Shootout in Naples, Florida.
The duo opened up with five successive birdies in the scramble format over the Gold Course at the Tiburon Golf Club.
Although they could not continue that on the par-five sixth, a couple more strokes were swiftly picked up ahead of the turn, which Stricker and O'Hair - who have each won the event hosted by Greg Norman before with different partners - reached at a seven-under 29.
By the time the pair strolled up to the par-three 16th, they were on 12 under before an impressive putt from Stricker landed an eagle three on the penultimate hole and the slick round finished with a birdie.
Irish duo Shane Lowry and Graeme McDowell are five shots off the lead on -10 which included ten birdies.
Keegan Bradley and Brendan Steele are one shot behind following a 14-under round which included 12 birdies and an eagle, sunk on the opening par-five hole.
Brandt Snedeker and Bubba Watson sit in third place after a 13-under 59, with an eagle at the par-four seventh.
Lexi Thompson, the only woman in the field, is tied for ninth after she and Tony Finau carded a nine-under 63, which saw a bogey on the par-three fifth.
Saturday will be played on a modified alternate-shot format, with Sunday's conclusion over a better-ball round.