Heavy rain delayed the start of the first major championship of the year by 5 1/2 hours. When play did get started, blustery winds created high scores and bizarre events.
Tiger Woods putted his ball off the 13th green into Rae's Creek and also suffered a bogey at the par-4 first when a seemingly perfect shot hit the flagstick and ricocheted into a bunker.
Billy Casper, meanwhile, shot the highest score on any one hole in the history of the tournament. He had a 14 at the par-3 16th hole en route to a 106.
DiMarco was 4-under with four holes to play when darkness fell, one shot ahead of Masters rookie Mark Hensby.
Hensby was one of 21 players to complete the first round. Luke Donald was also at 3-under through 14.
Woods was 2-over through 12 and Ernie Els was 3-over through 11.