Seamus Power made a fine start to the Rocket Mortgage Classic in Detroit and lies just two shots off the lead after carding a five-under par round of 67.
It's a three-way lead at the top, with Doc Redman, Kevin Kisner and Scott Stallings setting the pace on –7.
Redman, a 22-year-old from North Carolina, went from even par after 10 holes to finish with a 65 thanks to seven birdies in his last eight holes.
"I've come off two good finishes and a really good finish last year at this event, which has never really happened to me," Redman was quoted on the PGA Tour website as saying.
"So, I've never had this kind of expectation externally or even internally."
Waterford’s Power is among a cluster of players two shots adrift, including Rickie Fowler, and didn’t drop a shot in the opening round.
Four birdies on the front nine, with another at the par four 13th have him well placed going into the second round.
World No 10 Bryson DeChambeau was among a group of seven sharing fourth on six under, his day capped by a 33-foot putt for an eagle three at the 14th.