Matt Kuchar remains the man to catch in the FedEx Cup play-offs after opening the BMW Championship with a superb seven-under-par 64 at Cog Hill today.
The American Ryder Cup newcomer, now in with a great chance of the $10m (€7.87m) jackpot in a fortnight's time, had an eagle and six birdies to be one ahead of compatriot Ryan Moore.
England's Luke Donald and Justin Rose, meanwhile, set off with 68s and shared fourth place midway through the day's play.
Kuchar started the four-tournament series by beating Scot Martin Laird in a play-off for The Barclays title in New Jersey and maintained top spot with a 11th place finish at the Deutsche Bank Championship in Boston on Monday.
The 32-year-old picked up his first shot with an amazing 63-foot putt on the short 12th - his third - and then needed only a 10-footer for an eagle at the 526-yard 15th.
With birdies at two of the next three holes Kuchar turned in a five under 31. Three more birdies came on the outward half, including a closing 18-foot putt, but he did bogey the 383-yard eighth after going from one bunker to another.
Moore, another former US Amateur champion, came bursting out of the pack with seven birdies in eight holes from the 11th for an inward 29.
Donald, joint second on Monday five strokes behind American Charley Hoffman, and Rose both had six birdies and three bogeys, while Hoffman had to be content with a 70 and Laird managed only a two-over 73, the same as Londoner Brian Davis.
"Three bogeys was a little disappointing just because I didn't short game it well enough from relatively simple up-and-downs," said Donald, playing in his adopted home city of Chicago.
Tiger Woods and Phil Mickelson were among the later starters, as were Donald's cup teammates Rory McIlroy and Ian Poulter.
Woods probably needs a top five finish - something he has not managed since the US Open in June - to be among the 30 points leaders who advance to the Tour Championship in Atlanta.
Poulter and McIlroy, 44th and 29th in the standings respectively, both made bad starts, the former with a double bogey at the 10th and the 21-year-old Ulsterman with back-to-back bogeys.