Jordan Spieth is closing in on a season-opening win at the Hyundai Tournament of Champions in Hawaii after shooting a third-round 65.
The world No 1 has extended his lead to five shots but his nearest pursuer is now fellow American Brooks Koepka, who shot a 10-under-par round of 63 at Kapalua, the best of the tournament so far.
However, Spieth has reached 24-under for the event and is on course for a seventh PGA Tour win at the age of just 22.
He began the day with a four-shot advantage and was soon on the birdie trail, making four in a row from the third before his first dropped shot of the week came at the par-three eighth.
And Spieth's lead had dwindled to just one on the back nine before his putter got hot again as he rolled in a 46-foot birdie putt on the 12th, before picking up further shots at 14 and 15, and then eagling the last, following an amazing second shot which brushed against the flag-stick.
Koepka birdied six straight holes, beginning at the par-four third, and finished with 10 birdies altogether in a flawless round which took him to 19-under, a shot clear of first-round leader Patrick Reed (67).
The top three appear set to fight it out because Reed is a further three shots clear of Brandt Snedeker (65) and Fabian Gomez (70), who are in a tie for fourth at 15-under.
Kevin Kisner began the day in joint-second but could not keep pace and fell into a tie for sixth after a two-under-par 71.
Ireland's Padraig Harrington is just outside the top ten after a round of 70 took him to 11-under and world No 2 Jason Day, back in action after a three month break, shot a 69, his best round of the week so far, but is well back on seven-under, in a tie for 20th.
While naturally pleased with his position, Spieth does not consider it job done.
"To be honest, if I shot eight under I would expect to be seven or eight shots clear," he said. "So for Brooks to get that score is insane.
"I have to go out and hit birdies, I have to expect Brooks and Patrick to fire eight or nine under tomorrow.
"This is the furthest under par I have been after three rounds and there's no complaints from me on that one, but there are 18 hard holes ahead and the conditions are good, so there needs to be more birdies."
Koepka was unsurprisingly in good heart after his superb round and said: "Today was the day, perfect numbers, everything went my way. I flushed it."
Watch final-round action from the Tournament of Champions in Hawaii live on Sky Sports 4 from 11pm on Sunday night, or watch without a contract on NOW TV.