The American holed 10 birdies and a bogey in his third round at the TPC Summerlin, putting himself in a good spot for his maiden PGA Tour title.
Martin sits at 17 under in Las Vegas, two shots clear of Scot Russell Knox (66).
On a good day of scoring, Americans Jimmy Walker (62) and Andrew Svoboda (67) are tied for third at 13 under.
Martin had a solid front nine with four birdies and a third-hole bogey but he found his best form from hole 10.
He birdied the 10th and made five straight from the 13th as he got through the back nine in 30.
Knox went through bogey-free, while Walker did likewise but made the most of his opportunities.
Walker started on the back nine and produced four birdies with another five on the front nine to move into contention.
Svoboda could be closer if not for an inconsistent showing, making four bogeys, an eagle and six birdies.
A group of four Americans – Kevin Streelman (63), Brooks Koepka (64), Scott Piercy (67) and Webb Simpson (67) – are tied for fifth.
Simpson, who won the tournament by six shots last year, has been consistent, but needs a big finish if he is to defend his title.
There are eight players tied for ninth at 11 under.
German Alex Cejka, Canadian David Hearn and Scot Martin Laird are joined by Americans Bill Lunde, Jason Bohn, Brandt Snedeker, Jim Herman and Spencer Levin.