McCarron birdied holes 13-16 and No. 18 en route to a 9-under-par 63 at the TPC at Summerlin. His 26-under 262 total is a new 72-hole tournament scoring record; breaking the record of 263, set by four players in 1991.
McCarron likes his odds of winning on Sunday. This is the same tournament where he won enough money to keep his PGA Tour card as a rookie in 1995.
Its a lot of fun for me to play here, McCarron said. I will be here every year.
Tom Lehman, who set a 36-hole PGA Tour scoring record by playing the first two rounds in 19-under, is three shots off the lead following a 67.
Overnight leader Craig Parry (70), Bob Estes (68) and Rory Sabbatini (63) are tied for third place at 21-under.
Not only did Sabbatini shoot a personal best on Saturday, but did so with a strained Achilles tendon.
'It's actually been an advantage,' Sabbatini said. 'It takes my mind off things between shots. It makes me play one shot at a time which is the way you want to play out here.'
McCarron, who won this years BellSouth Classic, is currently 34th on the money list. The top 30 in earnings qualify for the $5 million Tour Championship, which takes place in three weeks; the top 20 by years end gain berths into each of the four majors in 2001.
This weeks top prize is $810,000.
Lehman is also trying to earn a trip to the Champions Golf Club in Houston, TX. He stands in 36th position on the money list.
Lehman started his fourth round with a 40-foot birdie putt at the 1st and had the outright lead after his third birdie of the day at the 7th.
However, he bogeyed three of the next five holes, and needed to birdie three of his final six holes to stay within striking distance.
Im disappointed with the bogeys I made but I felt I played reasonably well, Lehman said. I just kind of lost the feel a little bit.
McCarron had the feel on Saturday, carding nine birdies and no bogeys. But he knows three shots can dissipate quickly in the desert.
Youve got to make birdie out here, he said. No lead is comfortable. These guys are going to be shooting low scores tomorrow.
Im going to enjoy going out there trying to shoot for birdies. Being aggressive is the way I like to play anyway.
Full-field scores from the Invensys Classic