Both Lowery and Cejka shot 6-under-par 65.
Bo Van Pelt, Jerry Smith, James Driscoll and Brent Geiberger are tied at 5-under 66. Three-time winner Mark Calcavecchia leads a group of 12 players at 4-under 67 -- including Paul Stankowski, Kirk Triplett, Lucas Glover, J.J. Henry and Thomas Levet.
Neither Van Pelt nor Smith has ever finished higher than third in a PGA Tour event.
The round was called late in the day because of darkness, with four players left on the course.