Fresh from his Canadian Open win, Rory McIlroy headed to the US Open full of confidence, and it showed as the Northern Irishman raced into the lead early on.
But despite being top of the leaderboard after day one, McIlroy found himself three shots off the lead heading into the fourth and final day.
A poor showing on day three saw McIlroy shoot three-over par for a total of 73, leaving him scrapping to keep up with the leading pack.
Now just one-under-par, he has his work cut out for him on Sunday if he is to claim a fifth major title - and a first since 2014.
"It was one of the toughest days on a golf course I've had in a long time," McIlroy told reporters. "I just needed to grind it out, and I did on the back nine.
"To play that back nine at even par today was a really good effort, I thought - kept myself in the tournament.
"I'm sort of going home thinking that I held this round together when it could have got away from me quickly."
McIlroy's frustrating session started with three bogeys in the first six holes, while his back nine performance just about kept him in contention.
In contrast to McIlroy, Matt Fitzpatrick and Will Zalatoris both enjoyed superb showings in day three, with the pair scoring 68 and 67 respectively to head into the final day as joint leads on four-under.
If McIlroy is to turn it around and claim the title, he believes he'll need a showing as good as Fitzpatrick and Zalatoris in round four.
"I know guys aren't going to go out there and shoot the lights out," he added.
"I mean, 67 from Will out there today is unbelievable, such a good score, 68 from Fitz as well. I think, depending on the conditions tomorrow, that's what it's going to take.
"From me, it's going to take something like that to get the job done, but as we've seen today, things can change so quickly. I certainly thought I was going to be a few shots further back than I was at the end of the day."
You can follow the live leaderboard from the final day here.