Russell Knox carded a nine-under-par 63 to earn a one-stroke lead after the opening round of the Safeway Open, where Jordan Spieth's struggles continued.
The coronavirus-hit 2019-20 PGA Tour season came to an end following Dustin Johnson's Tour Championship and FedEx Cup success on Monday, but the new campaign already got underway on Thursday.
Knox, who missed the FedEx Cup playoffs by two spots, posted the Safeway Open's lowest opening-round since 2016 as the Scotsman ended the day ahead of Sam Burns, Cameron Percy and Bo Hoag.
A two-time PGA champion, Knox was flawless thanks to an eagle and seven birdies at the Silverado Country Club in Napa, California, where the first round was suspended due to darkness.
Brendan Steele – a two-time Safeway Open winner – is two shots off the pace following his seven-under-par 65, along with Pat Perez.
With the U.S. Open on the horizon, five-time major champion Phil Mickelson signed for a 71 to open proceedings, while Sergio Garcia ended the day a stroke further back in a tie for 99th.
It was another tough outing for former world number one Spieth, who shot a one-over-par 73 to be well adrift of leader Knox.
Without a top-10 finish since February's AT&T Pebble Beach Pro-Am and winless since the 2017 Open Championship, Spieth had three bogeys and two birdies in round one.