LAS VEGAS, October 20, 2013 (AFP) - Simpson completed 54 holes at Summerlin course at 19-under-par 194. On Sunday, he will be aiming for his fourth career win on the PGA Tour and first since the 2012 US Open.
Simpson said he made some slight changes to his swing Saturday after receiving some advice from his caddie.
"On the back nine I got some birdies going," said Simpson. "My caddie gave me a pointer and I starting swinging good down the stretch. Thanks to him I got it going on back nine.
"The better I play the harder it is going to be for them to catch me."
Chesson Hadley also shot 67 during his third round and is in second place at 15-under, while Jeff Overton (68) sits in third at minus-14 and Jason Bohn (69) has sole possession of fourth at 13-under.
Sean O'Hair carded the low round of the day with an eight-under 63 to vault into a share of fifth place with Japan's Ryo Ishikawa (68), Ryan Moore (69), Russell Knox (69), J.J. Henry (70) and William McGirt (64) at 12-under 201.
Simpson had six pars and a bogey on the front nine. After another bogey on the par-four 11th he posted four birdies over the next five holes.
"The greens are a little more firm today and I was too tentative at the start," said Simpson.
The tournament is the second in the US PGA Tour's new-look 2013-2014 program.
Six tournaments are scheduled before January, offering FedEx Cup playoff points and a coveted Masters berth to the winner.
Leading third-round scores on Saturday in the $6 million US PGA Shriners' Hospitals Open (USA unless noted, par-71)
194 - Webb Simpson 64-63-67
198 - Chesson Hadley 65-66-67
199 - Jeff Overton 63-68-68
200 - Jason Bohn 67-64-69
201 - Sean O'Hair 66-72-63, William McGirt 71-66-64, Ryo Ishikawa (JPN) 67-66-68, Ryan Moore 69-63-69, Russell Knox (SCO) 67-65-69, JJ Henry 60-71-70
202 - Andrew Svoboda 68-67-67, Brendon Todd 67-68-67, Daniel Summerhays 66-68-68, John Senden (AUS) 65-66-71