Marc Leishman fired five birdies in a three-under par 68 on Saturday to stretch his lead to five strokes over fellow Aussie Jason Day and Rickie Fowler in the BMW Championship.
Leishman started the day with a three-shot lead. His solid performance at Conway Farms put him on 19-under 194 going into the final round of the penultimate tournament in the US PGA Tour's FedEx Cup playoff series.
Day and Fowler both carded one-under par 70s for 199.
England's Justin Rose signed for a 66 that put him in solo fourth on 201.
Spain's Jon Rahm carded a 65 to head a group of seven players on 202.
Leishman capped his round with a birdie at the par-five 18th to put himself in prime position to seize a third US PGA Tour title on Sunday.
The most recent of those came at the Arnold Palmer Invitational this year. But he came up short at TPC Boston two weeks ago -- when he went into the final round sharing the lead with Justin Thomas and Jordan Spieth.
After two birdies and two bogeys in his first seven holes, Leishman birdied the eighth to make the turn at one-under for the day, and picked up two more birdies coming in as the field failed to mount a challenge.
"Putting four good rounds together (is the biggest challenge)" Leishman said. "A lot of tournaments you put three rounds together. May not be in a row. Very easy to throw a mediocre round in there. Tomorrow I've got to try not to do that.
"After what happened at the Dell (in Boston), I've got extra determination to finish this one off and my game is in a better spot. I feel like this course sets up for me a little better than it did at Dell. Hopefully I can just play well, do the right things and not worry about the result too much, as hard as that will be."
Fowler opened with a 24-foot eagle, but had just one birdie and two bogeys the rest of the way. Day had two birdies on the front nine but one bogey with no birdies coming in.
"Bit of a grind out there today," acknowledged Day, who won the tournament in 2015. "With the way I was hitting it, I'm actually quite happy."
Sunday's drama will include not only Leishman's bid for the title, but also the race for the top 30 places in the FedEx Cup playoff standings.
Only the top 30 advance to the Tour Championship in Atlanta, where a $10 million FedEx Cup playoff bonus will be up for grabs.
Five-time major winner Phil Mickelson and Masters champion Sergio Garcia, who both came into the tournament in the 30s in the standings, were in a group tied for 15th, 10 shots off the lead and fighting to make it into the Tour Championship field.