Chris DiMarco, who lost to Singh in a playoff at the PGA Championship in August, bogeyed each of his last two holes to finish alone in second place at 10-under-par 206. Jonathan Byrd and Matt Gogel followed at 9-under-par 207.
Singh was in complete control over the first two rounds on the Mystic Rock Course at Nemacolin and it was more of the same in the early goings Saturday. Some late hiccups almost cost Singh the 54-hole lead, however, he was able to hang on.
'I had a good start and just couldn't get it going,' said Singh. 'My rhythm was not there today. I was just struggling to find it all day. I'm still in the lead by two so I'm not that disappointed.'
Singh kicked off his round after his second shot to the par-4 second landed 5 feet from the cup for a birdie. Singh then birdied the par-5 fifth but gave that shot back with a bogey at the very next hole.
At the par-5 eighth, Singh chipped his third shot inside 7 feet and ran home the birdie. Then things cooled off considerably for the Fijian on the back nine.
Singh hit a poor third shot that went through the green at the par-5 11th. He tried to bump his fourth shot up a little ridge and the ball came to rest just on top of the hill, dangerously close to running back down to Singh's feet.
He two-putted for a bogey from there and looked to be in trouble after his second shot at the par-5 16th found the water. Singh took a drop in the rough and played his fourth shot back into the rough near the green. With the prospect of putting up a big number, Singh chipped in for par and it was business as usual.
Singh wasn't as fortunate at the par-3 17th, however. His tee shot missed the green and his ball was left in an awkward position up against the rough. Singh tried a chip shot and sent his ball racing past the cup. He almost saved par, but tapped in for bogey to fall back to 12 under.
Singh then parred the 18th and was left with a two-shot lead heading into the final round, thanks in part to the misfortunes of his playing partners.
'I wasted a lot of shots today,' Singh said. 'I'm still feeling pretty good about my ball play. You got another day to make up.'
Ben Curtis quickly played his way out of contention as the 2003 British Open champion ballooned to an 81 Saturday. DiMarco held steady, however, and was given opportunities to overtake Singh but was never able to capitalize.
'Thankfully, Vijay didn't run away with the tournament today,' said DiMarco.
DiMarco hit his second to 8 feet for a birdie at the first and converted a 6-foot putt for a birdie at the fifth. He then landed his tee shot inside 18 feet for a birdie at the par-3 seventh to move within one of Singh at 12 under.
The 36-year-old found trouble of his own on the inward half after his approach came up short of the green at the par-4 14th. DiMarco bogeyed the hole but recovered with a birdie at the par-5 16th.
After Singh's bogey at the 17th, DiMarco was tied for the lead briefly until his par putt was also unable to find the bottom of the cup. DiMarco then bogeyed the last to fall two shots back.
'Obviously, I would have liked to have been a little bit better,' said DiMarco, who won this event in 2000. 'But, you know, nobody really did much. The course actually won today.'
Zach Johnson carded a 70 to join Kent Jones in a tie for fifth place at 8-under-par 208.
Stewart Cink followed at 7-under-par 209 along with Joey Sindelar, Duffy Waldorf, Len Mattiace, Pat Perez, Robert Gamez and Bob Burns.