Australia's Jason Day has climbed into contention at the US PGA Tour's Travellers Championship in Connecticut, but he has his work cut out to catch resurgent English veteran Paul Casey.
Already a two-time winner this year, former world No.1 Day shot a four-under-par 66 on Saturday to be tied sixth going into the final round.
However he is still six shots behind Casey, who produced a blistering 62 to claim a four-shot lead from American Russell Henley (67).
Casey matched his lowest score on the PGA Tour as he used his flawless long game to hit every green in regulation and highlighted his round with an eagle at the par-four 15th at TPC River Highlands in Cromwell.
The Englishman, in some of the most sparkling form of his career at the age of 40, has a 16-under 194 total.
Halfway leader Brian Harman (69) slipped back into a tie for third at 11 under with Anirban Lahiri of India (65) and American J.B. Holmes (65).
Australian Matt Jones is two further back at nine under.
Day is in a five-way tied for sixth with Americans Bubba Watson (67), Bryson DeChambeau (68), Beau Hossler (68) and Ryan Blaum (66).
Fellow Australian Matt Jones is a shot further back after a 70.
Casey credited his hot round to a lesson from coach Peter Kostis.
"On Thursday I had the big pulls going. Every long club in the bag was five, 10 yards left it felt like," Casey told CBS.
"We worked hard on it yesterday after the round. Posture wasn't good enough and I was standing too far from the golf ball. He had me on the range feeling like I was going to shank everything yesterday."
The lesson paid handsome dividends as Casey picked up six birdies to go with his eagle.
"I was between clubs, whether to even go for the green or not," he said. "We couldn't afford to be short so we went with a three-wood, a little soft cut in there.
"That's something I rarely see, 18 greens in regulation, so clearly whatever (Kostis) told me worked."