Lee Westwood moved just two off the lead after ten holes of his third round at the US PGA Championship in Atlanta.
But Luke Donald, the only player ahead of him in the Official World Golf Ranking got even closer and then fell back again.
Donald faced a ten foot putt on the short 15th to take a share of top spot - it would have made him a brilliant six under par for the day - but missed it and then fell five behind.
After failing to get up and down from a bunker on the 16th the English star, like Westwood chasing his first Major title, saved par on the short next after only just making it over the lake.
But then the 507 yard par four 18th cost him a double-bogey six as he drove into more sand and went in the water with his third shot.
"I am angry," he said after signing for a 68 and one under aggregate that left him back down in 17th place as the leaders, headed by little-known American Jason Dufner, approached the turn.
"I had something good going and I threw it away."
Asked if he would go away and bang his fist against a wall, kick a cat or something he replied: "I might punish myself in the gym.
"It's just a shame to waste it like I did. I worked so hard to get to five under.
"Those last few holes are tough, but on the third shot to 18 I was probably too aggressive with my line and just pushed it.
"I gave myself a lot of chances, that's the positive thing, and if I can go low tomorrow who knows? But obviously the finish leaves a bitter taste in my mouth."
Westwood, 14th at halfway and four behind, birdied the long fifth and 442 yard tenth to climb to three under.
He was up to joint sixth, but three back when Dufner, joint overnight pace-setter with compatriot Keegan Bradley, birdied the short seventh to reach six under.
Dufner led by one from ex-US Open Champion Jim Furyk, Bradley and their fellow American Brendan Steele.
Rory McIlroy, meanwhile, admitted to frustration as his hopes of a second Major title evaporated in the heat - despite one of the more extraordinary shots of his career.
The Northern Irishman managed only a four over par 74 and dropped outside the top 60 on seven over par.
He started with a three-putt six and was in the lake for another double bogey at the short 15th, but the most memorable moment came on the 207-yard 17th - scene of his triple bogey in the second round.
McIlroy, his right arm still bandaged after his incident with a tree root on Thursday, was perilously close to going into the water again.
But instead his ball hit the wall bordering the green, flew high up into the air and finished nine feet from the flag.
It left him wondering what have come of the week if the same had happened 24 hours earlier, when he came to the hole only two strokes off third place.
"That would have been nice," said the 22 year old US Open Champion, who came into the week as clear favourite.
"Yeah, I think there were two pivotal moments in this tournament for me - obviously the shot on the third on Thursday (the one he admits in hindsight he should not have attempted) and the six iron on 17 yesterday."
Although he added that his pronator muscle was still "quite sore", it was his putting that cost him dear.
"I couldn't get my speed at all an the greens. I've struggled with it all week," he said.
"I've got one more day to go. Hopefully give it my best and shoot a good score and take a couple of weeks off."
He is next due in action at the Omega European Masters in Switzerland on September 1-4 - it is the first event of The Ryder Cup race - and once home he thinks he might not hit a ball until he gets there.
"I'll just make sure that it's okay for a couple of weeks' time. I want to try to finish as high up in The Race to Dubai as I can.”
Westwood did not even wait until the fearsome closing stretch to undo a lot of his good work.
After missing a three foot birdie chance at the long 12th, he found sand off the tee on the 468 yard 14th. And after firing his second into the crowd he was 30 feet above the hole in three and three-putted.
At one under, he and Donald were six back as Dufner and Steele opened up a two shot lead on the chasing pack.
