After a storm-hit third round, Augusta leader Chad Campbell faces a final day of 32 nerve-racking holes.
US unless stated
-6 Chad Campbell (after 4 holes*)
-5 Tim Clark (SA) (5), Rocco Mediate (4)
-3 Tiger Woods (9), Padraig Harrington (Ire) (6), Phil Mickelson (5)
-2 Stephen Ames (Can) (9), Retief Goosen (SA) (9), Ernie Els (SA) (5), Vijay Singh (Fij) (4), Fred Couples (4)
* Play halted at 0040 BST, resumes at 1245 BST
Only 140 minutes of play were possible for the leaders on Saturday following a four-hour weather disruption.
The 31-year-old American birdied his first two holes to stretch his lead to four at eight under, but then bogeyed his next two before the light failed.
He now leads Tim Clark and Rocco Mediate by one stroke, with play resuming at 1245 BST on Sunday.
A damp but thrilling end to Saturday's play saw South Africa's Clark enjoy a great hour in the Augusta twilight.
He birdied the 1st, 2nd and 5th to improve from two under to five under and a share of second, and he has a 6ft putt for birdie at the short 6th when he resumes.
"The way I'm playing certainly bodes well," said Clark, who then quickly rejected the tag of favourite.
"It's certainly not me. It's going to be someone who's fit. It will probably be the one who is most patient, somebody who doesn't make any big numbers."
That person could very easily be Tiger Woods, who looked ominous as he picked up two shots in the nine holes he was able to complete.
Totally at ease with the truncated nature of the session and the challenge ahead, the world number one is now three under for the tournament, three behind Campbell.
"I wish I was better placed and more under par, but I have nine holes left to get a good round and then come out for the afternoon," said Woods.
The 30-year-old American was in a similar position last year when he went to bed after another rain-hit Saturday four shots behind leader Chris DiMarco with 27 holes to play on Sunday.
Woods, of course, would go on to win his fourth Green Jacket by beating DiMarco in a play-off.
"It was nice to make birdies and I had two nice par saves. I kept the momentum going and I am right there in the picture," he added.
Also on three under is Ireland's Padraig Harrington, who was two under for his round through six holes.
The third man on three under is Phil Mickelson. But it could have been so much better for the 35-year-old American as he started with three birdies only to bogey his last two holes before the hooter sounded.
One shot further back are five men who had contrasting fortunes on Saturday.
In-form Canadian Stephen Ames will be delighted with the two shots he picked up in nine holes, while South Africa's Retief Goosen should also be satisfied with his improvement to two under.
Ernie Els, on the other hand, took one step forward at the 2nd, only to hand it back at the 5th. He also missed a makeable birdie putt at the 3rd.
But then playing partner Clark missed an even closer putt that would have put him into a share of the overnight lead.
Vijay Singh and Fred Couples, however, will both be disappointed to have slipped back a shot in the four and five holes respectively that they managed.
Spain's Miguel Angel Jimenez, Northern Ireland's Darren Clarke and 2003 champion Mike Weir are some of the names in the bunch at one under par.
Jim Furyk was the big mover further down the leaderboard, taking advantage of his early start to improve from four over to level par with a 68.
The third round will resume at 0845 local time (1245 BST) with Campbell facing a huge challenge.
"It has been a long day for four holes. I would have liked the day to have gone a little smoother but it didn't cooperate," said Campbell.
"Eighteen holes is tough enough so 32 is going to be a real challenge."
And with "the big five" of Woods, Goosen, Singh, Mickelson and Els all within four shots of his lead, he will have to play the best golf of his life if he is to win his first major title.