Brandt Snedeker has shot an eight-under-par round of 63 to take the lead at the BMW Championship in Illinois.
Starting on the back nine, the American shot seven straight birdies in a bogey-free round at Conway Farms Golf Club, which sees him one ahead of Zach Johnson.
A win this week would see the 32-year-old from Nashville, Tennessee, who is vying for back-to-back FedEx Cup titles, jump to second in the standings before the points are reset.
Current leader Tiger Woods went around in 66 to share third place with Charl Schwartzel, Steve Stricker and Kevin Streelman.
However, qualification for next week's TOUR Championship, where one man will walk away with a cheque for $10m (£6.3m), looks all but over for Rory McIlroy (+7) and Lee Westwood (+9).
