Singhs back-to-back birdie finish was a part of a third-round 4-under-par 67. At 13-under, the two-time major winner is two shots clear of Billy Mayfair (69) and Jose Coceres (64).
Overnight leader Tom Lehman is now in fourth place at 10-under after shooting an even-par 71.
Singh is in search of his first U.S. victory since claiming the 2000 Masters title. However, he has won twice internationally this season.
Im not taking anything for granted, said Singh, who finished runner-up at The Players Championship and at Pebble Beach. I wont go out there too confident.
The 38-year-old Fijian birdied the 1st and 5th holes, but bogeyed the 7th and 9th to make the turn in even-par 36.
After another birdie at the par-4 10th, Singh caught fire down the stretch, birdieing three of his final five holes to take sole possession of the lead entering Sundays final round at the Harbour Town Golf Links.
Theres pressure anytime youre in the lead, said Singh. I like to feed off it, to psyche myself up knowing the guys have to catch me.
Likewise, Coceres birdied his final two holes. The 37-year-old Argentine eagled the par-5 2nd, and then added five birdies to his card for the low round of the day.
Coceres, who won the 1994 Heineken Classic and 2000 Dubai Desert Classic on the European Tour, is making his third stateside start this year. He missed the cut at the both the BellSouth Classic and the Masters, where his countryman, Angel Cabrera, led early in the fourth round.
I think that the way I was hitting the ball, striking the ball very well in the beginning of the year, I felt I had a lot of confidence, Coceres said through a translator. I think that I have made sort of the turn today.
Born in Chaco, Argentina, Coceres was one of 11 children who used to sleep five or six to a bed. He first took up the game when one of his brothers cut branches off a tree and fashioned a golf club. He used rocks for golf balls.
Mayfair, the 1987 U.S. Amateur champion, parred his first 13 holes on Saturday. He only recorded two birdies on the day ' both coming on the back-nine par 3s ' but he managed to make it around the course without a bogey.
Full-field scores from the WorldCom Classic