Jordan Spieth feels he just needs a few mid-range putts to drop in order to mount a serious challenge for the US PGA Championship.
Last year's runner-up surged up the leaderboard on Friday, moving into joint-second at one stage thanks to five birdies in his first nine holes.
Having started on the 10th, Spieth found life trickier on the front nine, eight pars and a bogey resulting in a 67 that left the two-time major champion three behind clubhouse leader Henrik Stenson.
"I'm hitting the ball fantastic," said Spieth. "I just can't get a putt to go in outside 10 feet.
"And from 10 to 20 feet, the amount of opportunities I've had that aren't that difficult, [if I was] up to my [usual] putting standards I would be five, six, seven strokes better right now.
"It feels like it's a bit of a struggle adapting line and speed control on the greens. Inside of 10 [feet], I made quite a few good birdie putts today to get me in contention.
"I'm striking the ball beautifully. Driver went a little astray, but overall I feel like I'm in a good position to make a run, I just need a couple good rounds."
There was a moment of controversy for Spieth on the par-four seventh - a hole he has now dropped three shots on through his first two rounds - when it took him a long time to get a free drop from casual water on a cart path.
"I just tried to find out exactly all the options I had and ultimately taking relief from casual water gave me the best opportunity to still drop it on the cart path, play it on the cart path," Spieth said.
"It took a while because of different drops. We weren't sure where my stance would still be and it wasn't full relief.
"Ultimately I still ended up playing with a toe in the water. Because the angle had changed from the angle of my stance looking at the pin, he [the rules official] said he was very happy with it, that it was relief and I was altering my stance to play a different shot, which is true, from where the other drop would have been, which is going right at it.
"It was really weird. It was as complicated as I've ever really had it. Took about as much time as I've ever taken on a free drop. I literally asked every question I could ask and I got every answer I could be to be content."
In the group behind Spieth, Patrick Reed went round in 65 to reach five under for the tournament.
"Out of my seven birdies, I think five of them were pretty much kick-in birdies," said Reed. "It's nice to hit it close and not feel like you had to make a lot of long putts, just a bunch of tap-ins."