Kevin Kisner tamed the devilishly difficult greens at Quail Hollow to assume a healthy lead at the end of his second round, but expects putting to become even tougher as the US PGA Championship heads into the weekend.
The American carded a second consecutive 67 to sit eight under overall, three ahead of Thorbjorn Olesen after the Dane was through 10 holes.
Kisner's compatriots Rickie Fowler (70) and U.S. Open champion Brooks Koepka - three under for the tournament after two holes of his second round - provided a more familiar feel to the top end of the leaderboard.
But Kisner warned his rivals of a greater challenge to come in the final major of the year.
"If anything, the greens are getting a little firmer, which is pretty incredible," he said.
"Four-iron on the last hole went 40 paces from land to finish. So they are extremely firm. You've got to be in the fairway to be able to get it on the green, and who knows, if this rain holds off and doesn't stay around, I can't imagine how much firmer they can get."
Kisner's card was highlighted by a chip-in eagle on the par-five seventh hole and he was pleased with the position he put himself in at the midway point.
"I'm just excited about the opportunity," he said. "I'm really fired up about it the way I'm hitting the golf ball. I haven't hit it this well this whole summer. A lot of averages finishes.
"When I start hitting it the way I am now, I play well. So I'm looking forward to the weekend and having an opportunity to keep making birdies and playing well."
Kisner, who is seeking his first major championship victory, has not fared well in the game's biggest events and is keen for that to change this week.
"I've been upset with how I've played in the majors so far in my career," added the 33-year-old. "I feel like I have the game to compete in majors and tons of 30th- to 40th-, 50th-place finishes. That's kind of been our goal for the year.
"We haven't played well in them yet this year, but every year you learn more about the majors and how to approach them.
"It's difficult to fly to the British Open and try to figure out how to do your preparation for that. This is probably the easiest one I've had to prep for because I know the golf course so well and I've been up here a lot. I feel real comfortable here and I really like the golf course."