Warren shot a 6-under 65 early in the day and Kevin Sutherland matched that score shortly before darkness forced the opening round to be suspended with 24 players still on the course.
Kenny Perry, Bill Haas and Charles Howell III were among those at 67 and Phil Mickelson joined Woody Austin, Boo Weekley and K.J. Choi in a large group at 68. Choi is the early leader in the season-long FedEx Cup points race.
Tiger Woods, who won by eight shots in his season debut last week, is playing on the European Tour this week and has the lead after one round of the Dubai Desert Classic.
Warren played a bogey-free round that included three birdies in his first four holes. His best finish on the tour has been a tie for second at last year's Reno-Tahoe Open.
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