Los Angeles - World No 1 Jordan Spieth chipped in for an eagle and grabbed seven birdies in a nine-under par 64 on Friday to surge four strokes clear of the field after two rounds of the US PGA Tournament of Champions.
After another lovely day on the par-73 Plantation Course at Kapalua, Hawaii, Masters and US Open champion Spieth had a 16-under par total of 130 and a four-shot lead over first-round leader Patrick Reed, Kevin Kisner and Argentinian Fabian Gomez.
Reed had four birdies in a four-under 69 for 134, while Kisner climbed up the leaderboard with an eight-under 65 that included an eagle and six birdies and Gomez carded a bogey-free 66 that featured seven birdies.
New Zealand's Danny Lee was alone in fifth after a 68 for 135.
Spieth said before the tournament that he hoped 2016 would prove a continuation of a stellar 2015 campaign that saw him grab two major titles among his five wins and add a runner-up finish at the PGA Championship and fourth-place at the British Open as well.
If the 22-year-old Texan claims his seventh US PGA Tour title this week, he would match the number Tiger Woods achieved before turning 23.
He cautioned, however, that with only 36 holes played in the elite event for last season's winners there was "a long way to go".
After birdies at five, six and eight, Spieth took command with an eagle at the par-five ninth where he chipped in 36 feet.
He birdied 13, 14 and 15, and added a last birdie at 18 -- where his 13-foot putt hung on the lip for a fraction of a second before falling.
It looked all but effortless, but Spieth said a 16-under over the final two days would be "difficult to duplicate".
"It just comes down to no bogeys," he said. "If I can continue to limit those or keep a blemish-free card, we're going to be in a good position because there's enough easy holes to take advantage of."
Reed, who had closed with an eagle on Thursday to seize the overnight lead, said his ball striking just wasn't quite as solid.
"Because of that even though I was hitting a lot of greens they just weren't getting as close as they were yesterday," he said.
Kisner eagled the par-five fifth and strung together three straight birdies from 10 through 12 among his six birdies.
He is enjoying his first outing at Kapalua courtesy of his victory at Sea Island in November - a win that followed four runner-up finishes in 2015, three of those in playoffs.
Australia's Jason Day, whose five wins last season included his breakthrough major at the PGA Championship, carded an even-par 73 - dropping three shots in the last two holes with a bogey followed by a double-bogey.
His three-under total of 143 left him tied for 21st in the field of 32.
British Open champion Zach Johnson was a stroke further back after following up an opening 75 with a 69.
Leading second-round scores on Friday in the $5.9 million US PGA Tour Tournament of Champions at Kapalua, Hawaii (USA unless noted, par 73):
130 - Jordan Spieth 66-64
134 - Kevin Kisner 69-65, Fabian Gomez (ARG) 68-66, Patrick Reed 65-69
135 - Danny Lee (NZL) 67-68
136 - Rickie Fowler 69-67, Steven Bowditch (AUS) 69-67
137 - Peter Malnati 71-66, Bubba Watson 69-68, Brooks Koepka 69-68
138 - Padraig Harrington (IRL) 70-68, Matt Every 70-68
139 - Smylie Kaufman 70-69, Brandt Snedeker 67-72
140 - Dustin Johnson 73-67, Bill Haas 71-69, Scott Piercy 71-69
141 - Jimmy Walker 70-71, Chris Kirk 70-71
142 - David Lingmerth (SWE) 71-71
143 - Troy Merritt 75-68, Russell Knox (SCO) 71-72, Jason Day (AUS) 70-73, Justin Thomas 70-73, J.B. Holmes 67-76
144 - Zach Johnson 75-69, Alex Cejka (GER) 72-72, Emiliano Grillo (ARG) 71-73
145 - Graeme McDowell (NIR) 75-70
147 - Davis Love 75-72
151 - J.J. Henry 77-74
152 - James Hahn 76-76