Shane Lowry began his Wyndham Championship bid with a two-under par 68, which left the Open champion six shots off the lead.
The Offaly man carded four birdies and two bogeys, the second of which came on the 17th hole, in his first round in Greensboro, North Carolina.
Harold Varner III shot an eight-under 62 to share the first-round lead with Tom Hoge and Roger Sloan.
The American's eight-birdie, no-bogey round at the Sedgefield Country Club in Greensboro, North Carolina, matched his career best on the PGA Tour.
Canada’s Sloan birdied on the 16th and 17th holes and could have moved into an outright lead but failed to sink a 15-foot birdie on the final hole.
The trio were two shots ahead of Harris English while Wesley Bryan led a large chasing group in fifth which included former Masters champion Patrick Reed with a five-under 65.
Seamus Power sits alongside Lowry on two under, and the Waterford man's round consisted of five birdies and three bogeys.
Graeme McDowell finished on three over par.
There were 33 players still on the course when bad weather suspended play.