Los Angeles - Australia's Rod Pampling followed up his scintillating first-round 60 with a three-under par 68 on Friday to maintain a one-shot lead in the US PGA Tour tournament in Las Vegas.
Second-round play at TPC Summerlin was suspended because of darkness with 19 players still on the course.
Pampling's 14-under par total of 128 put him one stroke in front of American Brooks Koepka, who carded a 67 for 129.
Aaron Wise was 12-under for the tournament with four holes remaining when play was halted, and Chris Kirk was in the clubhouse on 11-under 131 after a 65.
Pampling appeared to feel some letdown after challenging for a 59 on Thursday, opening with two bogeys in his first five holes.
He recovered by playing his last 13 holes in five-under with six birdies.
"Just two silly mistakes that I made," Pampling said of his slow start. "I knew things were still good. I didn't panic. I made a good one on I think it was our sixth hole for birdie and then made a great up-and-down on 16. That just kind of righted the ship, and then after that I was fine, and we played nice after that."
Koepka, ranked 22nd in the world, grabbed a share of the lead after an eagle at the par-five 16th, but dropped a shot with a closing bogey.
Kirk, whose 36-hole total of 131 was his lowest since a 130 at the 2013 Sony Open in Hawaii, briefly held the clubhouse lead.