Brendan Steele started the defence of the Safeway Open with a seven-under round of 65 to hold the joint lead in the first PGA Tour event of the season.
The American had a favourable bounce on the approach to the par-5 fifth and holed the subsequent putt to eagle the hole in a round which included six birdies.
The sole blot on his copybook was a bogey on the sixth hole in Napa, California, where he leads alongside fellow Americans Tyler Duncan and Tom Hoge, the latter hitting six birdies on the back nine to put himself into contention.
Phil Mickleson, 42 time PGA Tour winner, ended the day tied for 12th place with a 3-under round of 69.
Back-to-back birdies on the ninth and 10th were cancelled out by dropped shots on both the eighth and 15th
Sangmoon Bae carded a one-over 73 on his return to the PGA Tour after serving military service in his native South Korea, dropping four shots in a row but scoring birdies on the 12th and 18th.