A 13-times winner on the European Tour, Casey played in three Ryder Cups but was controversially left off the 2010 team despite being one of the world's top ranked players at the time.
On Sunday, the 39-year-old put himself in pole position for just his second PGA Tour victory in 194 starts when he eagled the final hole to take a three-shot lead in the third round at TPC Boston in Norton.
The Englishman's approach shot from 235 yards at the par five landed just in front of the green and rolled up to inside a foot of the hole. He tapped in for a third consecutive 66 and a 15-under 198 total, with American Brian Harmon (68) in second place on 12-under.
“It was more of the same great ball-striking,” Casey told Golf Channel. “Attitude was great as well.
“I’m loving that I’m in the lead. I’ve had a few events out here and only got one win, so I’d love to double that tally.
"If it doesn’t happen tomorrow, I’m pretty confident it will happen relatively soon.”
Officials brought forward the final-round tee times to early Monday due to weather concerns over a hurricane that is expected to pass off-shore during the day.
Harmon, who also has one Tour victory, moved into second place with a tidy four-birdie performance.
Americans Jimmy Walker, Kevin Chappell and Smylie Kaufman are four strokes behind Casey in the second of the PGA Tour’s four FedEx Cup playoff events.
Halfway leader Chappell plodded to a 71 which included a double bogey at the par-four 12th, where he took four strokes to hole out from just off the green.
PGA Championship winner Walker (70) made a poor start with two bogeys in the first three holes, while Kaufman (68) also started slowly with a bogey at the par-five second.
(Reporting by Andrew Both in Cary, North Carolina; Editing by Ken Ferris/Peter Rutherford)
