Tiger Woods shot a five-under 65 in the second round of the Quicken Loans National in Maryland to move to four shots off the lead.
The American, who carded a 70 in his opening round, is using a new putter at the tournament and hit seven birdies and two bogeys to go to five under.
Compatriots Ryan Armour, Brian Gay and Beau Hossler are joint leaders on nine under.
"You've got to be patient on this course," said 42-year-old Woods.
"There's not a lot of low scores out there."
He added: "I tried to clean up my ball-striking a little bit and continue doing what I was doing on the greens in the first round.
"I hit a lot of good putts on Thursday, they just didn't go in. I started on my line with the right pace and today I did that and a lot of them fell."
Italian Francesco Molinari is one shot behind the leaders after a second round 65, while Ireland's Seamus Power is on four under after scores of 66 and 70.