Kapalua - Defending champion Patrick Reed eagled the 18th hole on Thursday to pip world No 1 Jordan Spieth for the first round lead at the PGA Tour Tournament of Champions in Hawaii.
Reed, who has six top-10 finishes in his last six tournaments around the world, played his last six holes in six-under par to seize the lead with an eight-under par total of 65 on the par-73 Plantation Course at Kapalua.
Spieth, off to a solid start in his mission to carry his scintillating 2015 form seamlessly into the new year, birdied the last to cap a 66.
Both were part of a five-way tie for the lead as they arrived at the par-five 18th, where Reed fired his second shot to 16 feet and made the putt.
New Zealand's Danny Lee finished tied with Americans Brandt Snedeker and J.B. Holmes on 67, with Argentina's Fabian Gomez alone in sixth on 68.
Spieth, whose stellar 2015 campaign included five victories, two of them majors, drained a 30-foot birdie putt at the second hole to get his 2016 on track.
"It's just a day to get into a rhythm, kind of see where everything's at," said Spieth, the Masters and US Open champion.
"Everything feels pretty good. I just need to tighten the gap a little, maybe have a couple better looks at birdie. But I can't complain."
"If I do what I did today each day, we're in good business," added Spieth, who had seven birdies in his bogey-free round.
Reed picked up just two birdies on his outward run and said the second, at the par-five ninth, was a turning point.
"From there I just hit the ball a little closer and hit better putts," he said.
Australia's Jason Day, whose five victories in 2015 included a major breakthrough at the PGA Championship, opened with a three-under par 70.
Reigning British Open champion Zach Johnson was well off the pace on two-over 75.
The 2015/16 PGA Tour season has been underway since October, but the first event of the calendar year is a highlight featuring only last season's tournament winners, with 32 taking part.
They were greeted by benign conditions, with little wind on a course softened by pre-tournament rain.
"I would call it as easy as the course could play," said Spieth. "You can attack some pins if the wind isn't blowing out here."
He and Reed will play together again on Friday, continuing a rivalry that has already seen the 20-somethings duel in two PGA Tour playoffs.
Reed came out on top at the 2013 Wyndham Championship, and Spieth avenging that defeat at the Valspar Championship last March in a playoff that also included Sean O'Hair.
"Maybe we want to beat each other so bad it brings the best out in us," Spieth said.
Leading first-round scores on Thursday in the $5.9 million PGA Tour Tournament of Champions at Kapalua, Hawaii (USA unless noted, par 73):
65 - Patrick Reed
66 - Jordan Spieth
67 - Brandt Snedeker, J.B. Holmes, Danny Lee (NZL)
68 - Fabian Gomez (ARG)
69 - Brooks Koepka, Steven Bowditch (ARG), Kevin Kisner, Bubba Watson, Rickie Fowler
70 - Smylie Kaufman, Padraig Harrington (IRL), Matt Every, Chris Kirk, Justin Thomas, Jimmy Walker, Jason Day (AUS)
71 - Peter Malnati, Emiliano Grillo (ARG), David Lingmerth (SWE), Russell Knox (SCO), Bill Haas, Scott Piercy
72 - Alex Cejka (GER)
73 - Dustin Johnson
75 - Graeme McDowell (NIR), Davis Love III, Troy Merritt, Zach Johnson
76 - James Hahn
77 - J.J. Henry
DNS - Jim Furyk