Curtis carded a 4-under 67 in the third round of the Booz Allen Classic on Saturday and stands at 19-under-par 194 -- a 54-hole tournament record.
'It's really nice out there,' said Curtis, 'other than being really hot.'
There were 12 players at 10 under par or better after the third round, but just one within five shots of Curtis.
Brett Quigley followed up his second-round 63 with a 4-under 67 on Saturday to get to 14-under-par 199. He stands alone in second place, one shot ahead of second-round U.S. Open leader and 1996 Booz Allen champion Steve Stricker (66) and Sweden's Daniel Chopra (67).
With bad weather expected on Sunday, players will start the final round in threesomes off split tees beginning at 7:00 a.m. local time.
Tee times Saturday also began at 7 a.m. on split tees. The rain held off, although players were still allowed to lift, clean and place their balls.
Curtis opened on the front nine with three straight pars, then reached 18 under with three consecutive birdies from the fourth hole, the last coming when he two-putted for a four at the par-5 fifth.
After a string of six pars, Curtis picked up his final birdie at the par-5 13th, where he found his only bogey of the tournament in the second round.
Saturday, he knocked his second shot 52 feet from the hole, then rolled it within 2 feet to set up the birdie.
Curtis hit all 18 greens in regulation during the third round. Considering that, he was disappointed with only being 4 under on the day.
'It's just a matter of making a couple of putts,' Curtis said. 'It could have been a really good score, but overall I'm very pleased.'
Curtis' 194 bested the old tournament record of 195, established by Hal Sutton in 1991 and matched by Adam Scott when he won in 2004.
Since his 2003 win at Royal St. George's -- he was the first player ever to win in his first start at a major -- Curtis has only held one 54-hole lead. That came at last year's Western Open, where he finished third.
'I would love to go out there (on Sunday) and birdie the first two or three holes,' said Curtis. 'You never know. If I don't hit the fairways, then it becomes tough. I'm not going to protect [my lead], by any means.'
Quigley began the day in a tie for fourth place, five shots behind Curtis. He collected three birdies on the front nine -- on 10-foot putts at the second and fifth, and a 5-footer at the sixth.
On the back nine, Quigley added birdies at the 10th and 15th, but also found a bogey at the 14th, where he three-putted from 18 feet.
'Playing with Ben will be good,' said Quigley. 'I know I need to shoot 5-, 6-, 7-, 8-, 9 under -- who knows what the number is. I'm going to see if I can do it.'
Nick O'Hern fired a 64 on Saturday to climb from a tie for 35th place overnight into a tie for fifth place. He was joined at 11-under-par 202 by Robert Allenby (66), Bart Bryant (66), J.B. Holmes (69) and Jeff Gove (71).
Jose Coceres, who began the day in second place, struggled to a 7-over 78 and tumbled into a tie for 26th place at minus-7.