An inspired Phil Mickelson held a five-shot lead at one point during round three of the PGA Championship at Kiawah Island.
He later had a putt to extend it to six.
But a back-nine wobble which featured a bogey at 12 and a double at 13 after finding water meant he ended the day with a precarious one-stroke advantage over the menacing figure of Brooks Koepka.
Koepka has won four Majors since the start of 2017 and has dominated scoring in these championships over the last five years.
But Mickelson has more than one rival to fend off on a final day where anything could happen if the winds pick up.
Here Planet Sport looks at the leading contenders for victory:
Phil Mickelson - 1st on 7-under (70-69-70)
After dropping three shots in two holes, it could have fallen apart for Mickelson but he steeled himself and could have got them all back but for a cold putter.
Still, it was a highly impressive display and to play the first 10 holes in 5-under was magnificent.
However, are there signs of tiredness? After 36 holes he was ranked 1st for Strokes Gained: Off The tee; after 54 he's down to 36th.
And yet, Phil still ranks 2nd for SG: Approach and had his best numbers in that category in round three. He's 1st SG: Tee to Green but may need the putter (28th SGP) to heat up if he's going to get over the line.
Mickelson has converted three times in five attempts when leading/co-leading after 54 holes of a Major. He's 21-for-36 in regular PGA TOUR events.
Brooks Koepka - 2nd on 6-under (69-71-70)
Beware, Major monster lurking! Koepka is the 13/8 favourite going into the final round and it's not hard to see why given his brilliant record at this level.
He's a quite ridiculous 84-under-par in Majors since the start of 2017 - an astonishing 61 shots better than anyone else over the same period.
Koepka won his first Major - the 2017 US Open - from this position when entering the final round in second place just one shot back. He's also won his last two PGA Tour events - the 2019 St. Jude and 2021 Phoenix Open - when chasing.
He's played the tough closing stretch (13-18) in just 1-over to suggest that he'll be able to grind it out better than most when it comes to crunch time on Sunday.
Ranks 1st for Approach but only 38th for SG: Putting which would be the only concern.
Louis Oosthuizen - 3rd on 5-under (71-68-72)
The South African is still to win on American soil but this is a golden chance to wipe out that curious record and land a second Major title.
History says he tends to be the bridesmaid from this position and one concern is that Oosthuizen has played the tough closing holes in a combined 5-over.
Another is that he drove and putted poorly in round three. He hit just five fairways and lost over three strokes on the greens.
He's just two shots back but will need to sharpen those areas up.
Kevin Streelman - 4th on 4-under (70-72-70)
The top three on the leaderboard are all Major champions; Streelman, by contrast, has never even posted a top 10 at this level.
That says the veteran has no chance despite his promising position although, of all the leaders, he's made the fewest errors (seven bogeys and no doubles or worse).
Streelman ranks 9th for SG: Tee To Green and 27th in SG: Putting.
Christiaan Bezuidenhout - T5th on 3-under (71-70-72)
One of three South Africans in the top five, Bezuidenhout looked as if his challenge would evaporate on Saturday when he opened bogey-bogey.
But the youngster is made of stern stuff and played the back nine in 2-under to haul himself back into the top five again.
This is new territory for him but he gives the impression that he has the game and mentality to be a regular on Majors leaderboards.
He's only 49th for SG: Tee To Green but Bezuidenhout tops the SG: Putting stats.
Branden Grace - T5th on 3-under (70-71-72)
Another determined South African who just won't give up just when you think things are getting away from him.
Grace was sliding down the board after bogeys at 11, 13 and 14, and still had the tough four closing holes to come. But he parred 15, 16 and 17 and then jumped back to 3-under - where he'd started the day - with a walk-off birdie.
He's fourth in birdies so far with 14, third for SG: Around The Greens and 10th for SG: Putting.
Bryson DeChambeau - T7th on 2-under (72-71-71)
We've waited for Bryson to take the tournament by the scruff of the neck but there's been too much snakes and ladders from golf's biggest hitter.
That was rather summed up at the end of his third round when he birdied 16 and 18 but took double bogey at 17.
DeChambeau is 2nd for SG: Off The Tee and 6th for SG: Tee To Green but his work on the greens has held him back; he's 57th for SG: Putting.
Of all those on page one of the leaderboard he's had the biggest struggles over holes 13-18, playing them in a combined 6-over.
Joaquin Niemann - T7th on 2-under (71-72-71)
In contrast to DeChambeau, the Chilean is 1-under over holes 13-18 so if he's near the lead when coming to those ultra-hard closing holes, Niemann could be one to watch.
Birdies at 11, 13 and 18 hauled him back into contention on Saturday and he ranks 2nd for Strokes Gained: Putting.
Niemann is also driving the ball well (6th for SG: Off The Tee) but he's lost strokes around the green on all three days so far.
Gary Woodland - T7th on 2-under (70-72-72)
Woodland is the fifth Major winner in the top nine and his 2019 US Open victory also came by the coast (at Pebble Beach).
He started the final round there with a one-shot lead so will have to do it differently this time as he'll begin five behind Mickelson.
Woodland must be rueing the three double bogeys he racked up on day three. He still shot even par but it could have been so much better.
The 36-year-old is 5th for Strokes Gained: Approach but he's hit just 12 fairways over the last two days and is 117th for Driving Accuracy.
The weather was due to be particularly gruelling in round four but latest forecasts suggest it won't quite be as windy as first thought.
That said, it will still be an ever-present factor at a steady 15mph so there's no faking it on final day.
Koepka looks the right favourite at 13/8 but the price looks short enough given how much danger lurks on each hole. There's also a niggling feeling that his putter is a hindrance rather than a help.
Mickelson at 3/1 with Paddy Power will have his backers but perhaps a large contingent of sentimental ones too.
Oosthuizen at 6/1 (Hills) could be a spot of value and surely he can't go through his career without a win Stateside. Having a Major in the bag already (2010 Open) will help his cause.
But perhaps the each-way value lies with Christiaan Bezuidenhout at 25/1, who sits four back.
It will be tough but he's held firm so far and doesn't really have any weight of expectation on him unlike most of those around him.