Brett Stegmaier produced a six-under display of 66 to take the outright lead at the Shriners Hospitals for Children Open before bad light brought his round to an end after 15 holes.
The American fired four birdies and an eagle on the 16th hole after starting the day on the back nine, which was enough to manoeuvre himself into a one-shot lead with three holes to play in his second round.
Compatriot Morgan Hoffman is one shot off the pace on 10-under for the tournament, along with Chad Campbell and Tyler Aldridge, after he posted a five-under round on day two.
Mark Hubbard is also well placed on nine-under before he was stopped from completing his second round by the delay on a score of two-under with two holes to play. Nick Watney, Brendon de Jonge, Cameron Tringale, Daniel Summerhays and Jimmy Walker are also two shots off the lead.
Stegmaier will begin the third round with a four-foot birdie putt on the seventh hole, with the chance to extend his advantage in Las Vegas.
