Dustin Johnson accepted he will need "some help" from runaway leader Brooks Koepka to have any chance of winning the US PGA Championship.
Koepka will carry a record seven-stroke lead into the final round at Bethpage Black in New York as he bids to retain his title.
Johnson is in a four-way tie for second at five under after carding a one-under 69 in the third round.
The world number one knows Koepka – who shot a 70 to get to 12 under and grab the biggest 54-hole lead in tournament history – is in control.
"I'm going to need some help from him," Johnson said.
"Then, I'm going to have to play very, very well."
Johnson was left to rue a poor back nine, where he mixed four bogeys with two birdies after reaching seven under at one stage.
The 2016 U.S. Open champion was satisfied with his form, but lamented some missed chances.
"I felt like I played well, just made too many bogeys. It wasn't one thing or the other. Wind got me a couple times," Johnson said.
"Hit some drives that I thought should have ended up better than they did.
"Seemed like every time I got just a little bit out of position, I made bogey. Missed quite a few short birdie putts. Missed a couple short par putts.
"Overall, I felt like I swung the golf club very well. I drove it well. I putted well. I missed a few short ones."