American Ryan Palmer and Australia's Jason Day are in a tie for the lead after the second round of the Deutsche Bank Championship.
Palmer had led by two shots after day one but could only card a level-par 71 at TPC Boston after a see-saw front nine saw him record three birdies, two bogeys and a double-bogey.
His back nine was more consistent with six pars but it also included a bogey on the 10th as well as birdies on holes 12 and 18 to move him to eight-under par at the halfway stage of the tournament.
Day began his second round strongly with five birdies during his front nine as he threatened to take the outright lead. But the Aussie could only manage one further birdie at the 16th and three bogeys at 12, 14 and 18 tarnished his day as he posted a three-under 68.
But the pair are just one shot ahead of American duo Matt Kuchar and Billy Horschel who both had rounds of 66.
Kuchar shot a first round of 69 but afterwards admitted that the news of the sudden death of his caddie Lance Bennett's wife Angela had affected him.
But Kuchar revealed that he felt more comfortable today despite admitting that he was thinking about Angela throughout.
"Today was easier. I think that's the natural progression of how these things work,” Kuchar said. (I) still felt like Angela was on my mind almost every hole, every shot. But yesterday I had a hard time following through a couple of times."
Five Americans are a shot further adrift on six-under par with Bill Haas, Russell Henley, Patrick Reed, Keegan Bradley and Webb Simpson all within touching distance of the leaders.
Europe's best hopes come in the form of Scotland's Russell Knox and Germany's Martin Kaymer as they sit on five-under par for the tournament.
Rory McIlroy is on three-under par as the world number one shot a second round of 69 to go with his opening day 70. The PGA Championship and Open Championship winner had three birdies and a bogey on his front nine but a double bogey on the 14th brought him back to level-par. But two birdies at the end of his round saw him go round in two-under par.
The Northern Irishman is one shot ahead of England's Ian Poulter who endured a disappointing second round. He carded a 67 during his opening round but a 73 on Saturday, which included a triple bogey on the 16th and a double bogey on the 1st, along with five birdies and two bogeys saw him slip down the leader board.
Poulter is expected to become one of Paul McGinley's wildcard picks as the European captain prepares his team for next month's Ryder Cup.
England's Luke Donald is also aiming to become a wildcard pick but sits on one-over for the tournament after carding a 74.