The German veteran birdied three of his last five holes to cap a flawless round which put him in pole position in his long search for a maiden victory on the PGA Tour.
Cejka, who won the last of his four European Tour titles at the Trophee Lancome in 2002, holds a slender lead over young American Brandon Hagy while Argentine Emiliano Grillo is one further off the pace.
Hagy, playing in only his third PGA Tour event, got off to a flying start with three birdies over the first four holes and he picked up further shots at eight and nine to turn in 31 before making it three consecutive birdies at the 10th.
But he slipped back with bogeys at the 14th and 16th, although he finished with a birdie-four at the long 18th to match Cejka’s 67 and take possession of outright second place.
Grillo mixed four birdies with a piar of bogeys as he added a solid 70 to his opening 69, while defending champion Chesson Hadley also fired a 70 to join six other players on three under par.
Jonathan Byrd (71) and Brendon de Jonge (70) are also among the share of fourth, and two-time major winner John Daly is at two under after a typically-erratic 70 featuring five birdies and three bogeys.
Former US Open champion Lee Janzen is six shots behind Cejka after carding 17 pars and a lone birdie in a 71, but David Duval was unable to build on his encouraging first round.
The 2001 Open champion, without a win since his triumph at Royal Lytham, stumbled to a four-bogey 74 that dropped him back to level par for the tournament, while former Master champion Trevor Immelman was among those to miss the cut.