John Rollins posted a 65 of his own to share third place with David Peoples at 13-under-par 131.
While Singh looks to carry his momentum into the weekend to make a run at the money title, it was the current money leader who took another step towards immortality on Friday.
Tiger Woods posted a 5-under 67 to finish at 11-under-par 133 for his 113th consecutive cut made, tying the old mark set by the legendary Byron Nelson.
Woods was steady in his round on the Magnolia Course and picked up his first birdie of the day at the par-5 fourth. Woods then birdied the par-5 eighth before taking on the par-5 10th.
The top player in the game hit a bad drive but bounced his second shot from the rough off the putting surface and into a bunker behind the green. Woods got up and down for the birdie and concluded his perfect play on the par-5s with a birdie at the 14th.
At the par-4 18th, Woods landed his approach within 10 feet of the cup and converted the birdie putt to finish four shots off the lead.
'I'm very proud. It's certainly not something that is easy to do,' said Woods. 'There are times when I obviously should have missed. With a little bit of luck and a lot of hard work, it certainly pays off in the end. I'm sure I will think about the record later. Right now I'm a little perturbed at myself for not making any putts today. That putt on 18 was the longest putt I made all day.'
Singh played the back side first at the Palm Course and managed only a birdie and a bogey over his first nine holes.
The 40-year-old caught fire on the front side, however, and vaulted to the top of the leaderboard thanks to a run of five straight birdies starting at the par-5 first.
Singh then eagled the par-5 seventh to put a stranglehold on the 36-hole lead.
'I was fighting my swing today a little bit,' said Singh, a three-time winner in 2003. 'I guess it is all momentum. If you have the momentum going on your side then it flows and it is going to go good.'
The Fijian has made a case as a contender for the money title, but Singh is well aware that the race will most likely remain undecided until the final round is over at the Tour Championship.
'I think I have a very good chance,' said Singh. 'The last week will be big. I think whoever wins that one will win the money title.'
Estes started at Magnolia's 10th hole and jumped out of the gate with birdies on each of his first two holes. Estes found trouble with a bogey at the 13th but responded with three consecutive birdies from the 14th to make the turn at 9-under.
At the par-4 second, Estes knocked an 8-iron inside four feet for the first of three straight birdies.
Estes then dropped his tee shot within five feet of the hole at the par-3 sixth for a birdie before rolling in a 15-footer for a birdie at the seventh.
'You have to keep making birdies at this tournament and I just tried to keep making birdies,' said Estes. 'I wasn't overly aggressive on every single shot I hit. It is just kind of hard to know what to say really sometimes when you play a round like that. I drove it okay. I hit it pretty good and made some shots.'
Davis Love III posted a 65 to join Bob Tway, Scott Verplank, Rocco Mediate and Brent Schwarzrock at 12-under-par 132.
Retief Goosen, Tom Carter, Tim Clark, Briny Baird, Dan Forsman and Fred Couples were two shots further back at 10-under-par 134.
The 36-hole cut fell at 5-under-par 139. Among those who failed to qualify for the weekend were Lee Janzen, Curtis Strange, Chris DiMarco, Peter Jacobsen and 2002 champion Bob Burns.