Long after he had completed his first round, Rory McIlroy returned to Baltusrol on Thursday evening to find the practice putting area.
It was close to nightfall when he and his coach Michael Bannon left after working for around an hour to find a remedy to McIlroy's problems on the greens, which were principally responsible for a first round of four-over-par 74.
His stats yesterday tell the story: 35 putts in his first round. Normally Tour players take 28 or 29.
This is not the first time that putting issues have caused McIlroy some angst, but it's becoming an all too common storyline this season.
"I play my game from tee to green," the Holywood man said.
"I've been driving the ball as well as I have ever I think. It's just when I get on the greens it's a different story. I'll need to try and figure it out for tomorrow and try to shoot something in the mid 60s and get myself back into it."
McIlroy is nine shots off the leader, the American Ryder Cup player Jimmy Walker (below) who shot a first-round 65.
After falling to 48th in the rankings this year and without a top-10 finish since March, Walker's primary aim this week is just to make the US Ryder Cup team again, especially with double points on offer here.
"I definitely wanted to play Ryder Cup this year and I don't know how much time there's left in that, but I know we do a lot of picks this year and the picks keep going," he said.
"Solid play at the end of the year could get you the nod so those are definite goals."
Arguably the most impressive rounds on Thursday were from two of the world's top five players, whose preparations for this final Major of the season have been severely curtailed.
Jason Day, with family health issues again disrupting his plans before a Major, only arrived here on Wednesday and squeezed in just one practice round. Yet the world No 1 scored a two-under-par 68 to leave himself inside the top 10 on the defence of his title.
Even more impressive, given the schedule of celebration and media appearances in his native Sweden over the last week or so, was the 67 of Henrik Stenson, who lifted the Claret Jug 11 days ago at Royal Troon in a historic British Open success.
"I felt very happy with my long game," he said. "It was a solid round. Not having enough time on the greens in the preparation kind of showed up on a few occasions, but all in all I couldn't really ask for more than this."