England's Matt Wallace made nine birdies in his last nine holes at the race to Dubai for the lowest round in the season ending tournament's history.
The 33-year-old shot a 12-under par 60 but it took the world No87 to 16-under par total and to the top of the leaderboard.
However, it's the first time that a player has birdied all nine holes of any half of the golf course.
Two Ryder Cup stars - England's Dubai-based Tommy Fleetwood and Norway's Viktor Hovland - both shot rounds of 66, but could not make a birdie on the par-5 18th hole and remained one shy of Wallace at 15-under. Denmark's Jeff Winther, assisted by two eagles on the back nine, moved into solo fourth place at 14-under after a round of 64.
Defending champion and world No3 Jon Rahm was in tied ninth place with a bogey-free 67, while world No2 Rory McIlroy finally came into his own with a 65 that elevated him to tied 19th place.
Wallace said he was unaware that he had a chance to shoot a 59. He missed his second shot on the par-5 18th to the right bunker and made his up-and-down for a birdie when an eagle would have cracked the 60 barrier.
"Kind of gutted now actually. It was a great opportunity to do it. I've done it at Moorpark on the West Course, which is only a par 68, but to do it out there would have been really special today," said Wallace, who had earlier missed a short four-footer putt for birdie on the seventh hole.
Asked if he'd sleep well given the $3 million winner's cheque within his grasp tomorrow, Wallace said: "I will. If there was a competition for sleeping, I'd be on the podium each time.
"Money doesn't drive me. It inspires me a little bit, but the bigger the tournament, I want to compete in them against the best players. I am happy we're doing that this week."
Fleetwood started strongly with four birdies in the first seven holes and then made a long eagle putt on the par-5 14th hole. However, a three-putt bogey on the 17th halted his momentum.
Still looking for his first win of the year, Fleetwood said: "It would be great. I'm very happy with the fact that you get to the final day of the year and I'm still playing well, still feel fresh and I'm still motivated and in contention. I take a lot of pleasure out of that.
"We will see tomorrow. It was great today. Out there playing with one of the best golfers in the world and trying to go toe-to-toe with Viktor. Just look forward to more of it tomorrow."
Hovland was bogey-free for the round. A win tomorrow would make him only the second player after Henrik Stenson in 2013 to win the Tour Championship of both PGA Tour and the DP World Tour.
Asked about the possibility of replicating Stenson, the world No4 said: "It would be cool. It's been a crazy year. This is another big one and would be really nice to have it on the resumé."
The $10.5 million season-ending championship has a limited field of 50 players. While the Race to Dubai has already been decided in McIlroy's favour, the top-eight players getting a share of the $6 million bonus pool will be determined on Sunday, as also the 10 PGA Tour cards on offer for the top-10 non-exempt DP World Tour members.