Duke and Nitties each shot a 5-under 65 at the TPC-Four Seasons course on a day in which 53 players broke par.
Brad Adamonis, Scott McCarron, Charles Howell III and Mike Weir were all a shot back, while the large group at 67 included Robert Allenby, Jesper Parnevik and Chris DiMarco. Matt Weibring, whose father D.A. Weibring led the refurbishing effort of the TPC-Four Seasons layout prior to last year's tournament, also had a 67.
Duke has had three runner-up finishes in 117 career tour events, but has wound up no better than 26th this year. He has missed the cut seven times in 13 tournaments during the 2009 season.
Nitties, a rookie, failed to qualify for the tour three straight years before finally making it this season. His fourth-place finish in Phoenix has been his best showing.
Defending champion Adam Scott, having missed the cut in his last five tour appearances, shot a 71 Thursday and will likely have to do better on Friday in order to play on the weekend.
Vijay Singh, who has struggled since undergoing early season shoulder surgery but who finished tied for ninth at the Players Championship, had a 70.