Adam Scott is one shot off the lead and tied fourth after the opening round of the Hero World Challenge in the Bahamas.
Scott had five birdies and an eagle in his round of five-under 67 to be one shot behind leaders Jimmy Walker, Zach Johnson and Paul Casey.
Joining Scott on 67 is Bubba Watson, Bill Haas, world No.1 Jordan Spieth, who had a hole in one on the par-3 second hole, and Brooks Koepka.
A missed cut in his last start and an ongoing swing change proved to be no handicap for Walker as he charged into a share of the lead.
The 36-year-old American, taking advantage of light breezes on a receptive layout softened by recent rain, birdied four of the last five holes as he fired a sizzling six-under-par 66 at Albany Golf Club in New Providence.
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That left Walker, a five-time winner on the PGA Tour, in a tie at the top with compatriot Johnson and England's Casey in the elite 18-player event hosted by Tiger Woods to benefit his foundation.
Walker, who has been working with his swing coach Butch Harmon on a different head move, was delighted to rebound from a missed cut at the Dunlop Phoenix in Japan last month with a scintillating eight-birdie display at Albany.
"I ran off to Japan on a whim and played really bad, I was kind of embarrassed," Walker told Golf Channel.
"Since then, I haven't been doing much but we really started working hard (on the swing) ... just a little head move, and I've had a hard time getting it. Doing it on the course is tough, it's a big change, but I did it pretty well today."
British Open champion Johnson, one of seven players ranked in the world's top 11 who are competing at Albany, joined Walker and Casey in a three-way tie for the lead after picking up five shots after the turn.
"I put myself in a position to make some putts," said Johnson. "The greens have gotten, the last two days, a lot faster and a lot better ... they are pure.
"There's no excuse on missing a putt. You hit it good on the right line, it's going to go in."
Spieth, who tied for second on his title defence at the Australian Open last week, was once again back in contention as a reigning champion -- this time after his hole-in-one and three birdies at Albany.
"I just needed to hit a nice punch-draw with a six-iron, 175 (yards) or so to the hole, it was playing about 185, 190," the 22-year-old Texan said of his ace.
"It was right at it but we didn't think it went in. I thought it was about 10 or 12 feet long after I struck it. It took a little while in the air to drop."
