Patrick Reed and Gary Woodland have set the first-round pace at the windswept World Challenge in The Bahamas, while tournament host Tiger Woods is six shots back.
Reed, Masters champion of 2018, and reigning US Open winner Woodland fired rounds of six-under-par 66 at the Albany Golf Club on the island of New Providence.
They sit two shots clear of Chez Reavie in the 18-man exhibition event.
Englishman Justin Rose, Swede Henrik Stenson and Americans Justin Thomas and Rickie Fowler were a further shot back after opening rounds of 69.
Defending champion Jon Rahm of Spain was four shots back of the co-leaders after mixing four birdies with two bogies.
The tournament began a day earlier than usual to accommodate golfers travelling to next week's Presidents Cup in Australia.
The field included all but one member of the 12-player US team that will compete at Royal Melbourne – with Dustin Johnson skipping the week as he continues his recovery from knee surgery.
Woods, the playing captain at the Presidents Cup, reached the turn at two-over par but made three birdies and an eagle over a five-hole stretch starting at the 11th to claw back up the leaderboard.
However, he endured a brutal finish to drop three shots in two holes and finish the day in a share of 11th
The World No.7 made bogey at the par-3 17th after he found the front bunker and closed with a three-putt double-bogey from about 12 feet for an even-par 72.
Woodland mixed eight birdies with two bogies to grab the early clubhouse lead but Reed, playing two groups behind, offset his only bogey with four consecutive birdies from the 13th to join his American compatriot atop the leaderboard.