Cameron Beckman and Luke Donald both shot 3-under 67s on Saturday and share third place at 9-under-par 201. Nick Price (66) and Per-Ulrik Johansson (67) are one stroke further back at minus-8.
Singh briefly lost his lead early in the round as he opened with five consecutive pars. He birdied the par-4 sixth to join Sluman atop the leaderboard at minus-11.
After a pair of pars, Singh dropped one stroke back again when he bogeyed the par-4 ninth. His second shot to the ninth came up short. Singh then knocked his chip over the back edge. He managed to up-and-down for bogey from there.
The Fijian played steady throughout the back side. He opened with three straight pars. Singh converted his final birdie of the day at the par-3 13th to grab a one-shot lead. He parred out from there to maintain his advantage.
'I haven't played this golf course with that wind,' said Singh. 'I was always unsure about what club to hit and the wind wasn't consistent. All in all, I thought I played pretty good and I made some good putts.'
Singh, who won the Phoenix Open earlier this year, will look to win his 13th PGA Tour title on Sunday.
'I'm still in the lead which is an important thing,' Singh said. 'They still have to worry about catching me. If I go out there tomorrow and maybe get one or 2-under earlier on, then I can relax a little. Today I was always around par and when you are around par you don't want to throw away shots.'
Sluman began the round two shots behind Singh. Sluman came out firing however as he birdied three of the first four holes to overtake Singh. Sluman cooled from there, as he could only par the next six holes.
The 1988 PGA Championship winner bogeyed the par-4 11th to fall to minus-10 and a share of the lead with Singh. Sluman ran off three straight pars, but dropped another stroke when he bogeyed the par-4 15th on the TPC at Las Colinas.
Sluman atoned for that mistake as he birdied the next to remain in second place by himself.
'It wasn't an easy day to play out there with the wind coming from a different direction,' Sluman said. 'The greens really firmed up, so it wasn't the golf course that we saw the first two days. But all in all I'm not unhappy certainly with my position.
'The shots I was hitting, I felt were pretty good shots and a lot of times they didn't end up in pretty good spots. That's the way it goes around here.'
Sluman knows the final round will not be easy with Singh leading the way.
'Obviously he is a major winner. He has won all over the world,' said Sluman. 'He is a big strong guy that hits it a mile and is fearless out there.'
Donald had two birdies and two bogeys on the front nine. He made a move on the back side however. He birdied the 12th and 14th before holing out from a greenside bunker for eagle at the par-5 16th that moved him to minus-10. He faltered though with a bogey at the last hole to fall into a share of third.
'I won late in the season last year and that was a great feeling,' said Donald. 'And I would love to win again. It's always nice to be in contention going into Sunday. I've played a little bit better than my scoring this year. I'm not surprised, I'm having a good week now. It was only a matter of time that I was getting the right bounces and making a few more putts.'
David Toms, who won the Wachovia Championship last week fired a 5-under 65 to jump into a share of seventh place with Hal Sutton (66), Hidemichi Tanaka (68), Peter Lonard (68), Andrew Magee (67), Robert Allenby (69) and Briny Baird (69) at 7-under-par 203.