Rory McIlroy, who won the Deutsche Bank Championship in Boston last week, was three under through 10 holes for a tie for 10th place at the BMW Championship when poor weather stopped play in the opening round in Indiana.
Robert Castro shot a seven-under 65 to take a one-shot lead at Crooked Stick Golf Club.
Play was delayed for three-and-a-half hours before darkness forced the first round to be suspended until Friday morning.
Castro was one of the players who was able to complete his round and he sunk eight birdies and a bogey to sit one shot ahead of Brian Harman.
"I told myself the last two weeks really to play like I had nothing to lose, and to make a bunch of birdies is a good way to start," Castro told reporters.
"Sure, it's a hometown tournament for me. It's the hardest one to get to, unfortunately, but it's still a great tournament. I would love to be back."
Jason Dufner and Dustin Johnson carded five-under rounds of 67, while Chris Kirk had five birdies in nine holes to join them before his round was cut short by the weather.
Portrush’s Graeme McDowell finished on one over, while Olympic champion Justin Rose was a disappointing three over through 16.
