Jordan Spieth continued to set a stunning pace in the Masters Tournament, but a brilliant 67 saw Justin Rose take the fight to the 21 year old at Augusta National.
Spieth – a runner-up here on debut 12 months ago and coming into the event on the back of first, second and second-place finishes, was seven shots clear at one stage but double bogeyed the 17th en route to a third round 70.
At 16 under par he leads by four from former US Open Champion Rose, who carded four gains in a row from the 13th and birdied the 18th to complete a remarkable inward 31.
Rose was two over par after five holes of the third round but played the remaining 13 in seven under, holing a bunker shot on the 16th.
And with Spieth following a wild drive with a poor pitch and three putts on the 17th, the American's seven shot lead had been drastically reduced to four, although he still set a new 54-hole scoring record at the Masters.
At 16 under par, Spieth broke the record shared by Ray Floyd and Tiger Woods by a single shot, with three-time Masters champion Phil Mickelson third on 11 under and Charley Hoffman on ten under.
World Number One Rory McIlroy and 14-time Major winner Woods were in a five-way tie for fifth, albeit ten shots off the lead after matching rounds of 68.
Spieth's halfway total of 130 had not only set a new Masters record but also equalled the lowest 36-hole total in Major Championship history and, at 14 under, was the lowest in relation to par.
The World Number Four was the fourth player to have a five-shot halfway lead in the Masters after Herman Keiser (1946), Jack Nicklaus (1975) and Floyd (1976) - all of whom went on to win - with Floyd the last man to hold the outright lead after every round.
Looking to become the second youngest champion ever - he is five months older than Woods was in 1997 - Spieth also became just the second player after Woods to reach 18 under par in the Masters when he carded his seventh birdie of the day on the 16th.
At that point he was seven shots clear of the field, only to take six on the 17th, while Rose finished in style to ensure he would be in the final group on Sunday.
Spieth, who led by two shots after seven holes of the final round last year, said: "Last year definitely left a bad taste and I have been looking to get back here and get some revenge but I have a long way to go still.
"It was weird because I had 24 hours from the time I finished on Friday to teeing off today and that's a long time to sit on a lead like that. I maybe got a little anxious at times but all in all kept it together with the putter."
Spieth was relieved not to have made matters worse on the 18th, slicing his approach into the crowd but getting up and down to save par.
"I thought two under would be a good score today but obviously being four under and closing at two under is disappointing, but it could have been worse and I was very pleased with that up and down on 18.
"It took some guts to hit that flop shot and the par putt was huge, one of the biggest putts I have ever hit.
"I was very frustrated. I didn't do any scoreboard watching until the 15th and then knew I was six clear and pars were good scores on the last two holes. Driver should never have come out of my bag at that point. I was getting a little erratic with the driver and could have hit three wood, eight iron."
Rose came from two shots behind Mickelson to win his first Major title at Merion two years ago and said: "I just remember being very patient, very focused. Just believing it was a 72-hole tournament, playing one shot at a time, not getting ahead of myself and also not being scared to lose.
"You have to put it on the line and you've got to make committed, aggressive swings under pressure. That's what I'm going to do tomorrow.
"My caddie and I were commenting that he (Spieth) was already at 18 under par, which was Tiger's record score. Jordan was so far ahead that you were just playing your own game.
"I was doing the right things. I hit a good tee shot on 13. I hit a good tee shot on 15. So I was doing all I could to make a score. But then the things like the bunker shot going in are a bonus, and obviously the 18th hole making birdie there.
"It was nice to stay patient and get rewarded with a hot finish. It's amazing and it put me in with a great opportunity tomorrow now. It's a great lesson, as well, to stay patient, because you never know when you're going to get your run.
"I think I just find it (Augusta) an inspiring place, really. Probably makes me no different to the other 96 guys who played this week. I have good memories around here.
"We always talk about the course fitting your eye and I guess it does for me. I've had good rounds. I've never put four together, so looking forward to that.
"I've got a good game plan around here. I've learned where you can miss it, where you can't miss it; which pins to be aggressive to, which you can't. I think that being here ten times now, I'm sort of beginning to put it all together."
