His blemish-free round puts him on 10 under par, clear of a group of 10 players sharing the second spot before darkness forced a suspension of play in Las Vegas with the last few groups still on the course
England’s Harry Hall was among those who carded an opening 64, three closing birdies following the only bogey of the round on his 15th hole.
A group of 10 is one stroke further back with another nine players, including former Open champion Francesco Molinari, at five under par on a congested leaderboard behind Pendrith.
Tom Kim, looking to complete a hat-trick of wins in the event, fought back from dropping three early shots to shoot a two-under-par 69.
Joel Dahmen, who sits 124th in the race to finish in the top 125 to secure a full PGA Tour card for next season, suffered a major blow when he was penalised four shots for carrying an extra club.
Dahmen discovered he had an extra four iron on the fourth tee and picked up the maximum penalty for carrying more than 14 clubs.
