Big-hitting American Cameron Champ fired an opening round of 65 to set the pace in the Sanderson Farms Championship in Mississippi.
Champ, who averaged 343 yards off the tee on the second-tier Web.com Tour last season, carded eight birdies and a solitary bogey at The Country Club of Jackson to finish seven under par.
That gave the 23-year-old Californian a one-shot lead over compatriot Cameron Tringale, with South African Rory Sabbatini and Argentina's Andres Romero part of a group a shot further back on five under.
Former US Open champion Lucas Glover was three shots off the lead thanks to a bogey-free 68, with defending champion Ryan Armour two under par after dropping his only shot of the day on the 18th.
Ireland's Seamus Power, who kept his PGA Tour card by just six points in the FedEx Cup standings last season, carded two birdies and one bogey in a one-under-par 71.
Scotland's Martin Laird returned a level-par 72 which was matched by world number 76 Dylan Frittelli, the highest ranked player in the field.
Fifteen players were unable to complete their round before play was suspended due to darkness.
