Shane Lowry and Graeme McDowell enjoyed solid starts to the Houston Open before the first round was suspended due to darkness.
Both players are tied for 12th on two under, though Séamus Power had a start to forget as he slid to four over through eight before play was halted.
Four players are tied at the top of the leaderboard, with three of the four on five under - Russell Henley, Talor Gooch and Marc Leishman - having completed their rounds, while Luke List was through 15 holes when play was called off.
List had an eagle on the par four 14th to push himself up the leaderboard, while Leishman could have held the outright lead but bogeyed the 18th.
Jason Dufner is a shot back from the leading group after signing for a 66, while six others are a shot back and tied for sixth, but four of them will resume their first rounds on Friday.
Tyrrell Hatton was another who struggled at the start, as the Englishman reached four over through nine, thanks in part to consecutive double bogeys.
