Henrik Stenson continued his fine form to open up a four shot lead at the Tour Championship in Atlanta.
Stenson had held the overnight lead at six under and a second round 66 saw him move to ten under, with Masters Tournament champion Adam Scott his nearest competition.
The Swede got off to a flying start as he made birdies at the first, second, fourth and ninth meaning he had played the front nine in just 61 shots over the first two days.
He went on to drop a shot at the tenth but a further birdie 16 saw him go into the weekend with a comfortable cushion.
The Swede knew that a win here would secure him the first prize of $1,400,000 and the $10,000,000 bonus for winning the FedEx Cup.
Tiger Woods, Scott, Zach Johnson and Matt Kuchar can also claim both prizes with a win this weekend but that now looks a near impossibility for Woods, who had looked on course to make one of his trademark charges before his round fell apart.
The 37 year old, who has five wins on the US PGA Tour this year, responded well to Thursday's disappointing 73 and was five under for his round through 13 holes.
But a double-bogey at 14 followed by another dropped shot on 16 and a triple-bogey on 17 saw him drop to four over for the tournament, 14 shots behind Stenson.
Scott endured a rocky front nine but two birdies to go with two dropped shots got him to the turn in par and a birdie at 16 had him out in second place on his own.
Jordan Spieth was a further shot back after firing a three under par 67 with Justin Rose, Dustin Johnson and Billy Horschel all sat on four under.
Keegan Bradley and Nick Watney both fired 65s to sit in the group at three under alongside Zach Johnson while Kuchar was three over following a disappointing 74.
Tournament organisers also announced that due to expected rain and possible thunderstorms on Saturday, players would be in threesomes for the third round and the first tee time had been brought forward to 7.30am local time (12.30pm BST).