It's been 83 years since a player this young won a major, and 35 years since anyone won the Masters on his first try.
Two shots behind was 50-year-old Miguel Angel Jimenez of Spain, rattling off seven birdies for a tournament-best 66 that gave him a shot at becoming the oldest winner in 154 years of championship golf. And still very much in the picture is Fred Couples, the 54-year-old who won his green jacket a year before Spieth was born.
The only mention of Tiger Woods, absent from Augusta National for the first time in 20 years, was whether Spieth could replace him as the youngest Masters champion.
"For a 20-year-old, he's pretty savvy. Not much bothers him," said Couples, who picked Spieth for the Presidents Cup. "Tomorrow obviously is going to be a really, really hard day to try to win this. But he's well qualified to do it."
Spieth managed one last par from the deep fairway bunker on the 18th hole for a 2-under 70. In his first Masters, he has broken par all three rounds.
That gave him a share of the lead with Watson, whose five bogeys in a round of 74 brought so many players back into the mix. Watson had a three-shot lead at the start of the third round. When he walked off the 18th green with a par, nine players were separated by three shots.
Spieth and Watson were at 5-under 211.
"Today was moving day," Spieth said. "And tomorrow is about seeing how I can control my game and emotions out on the golf course against guys that have even won here recently. So they have been in the position I haven't. Doesn't necessarily mean I don't think that they have an advantage in any way. I think that I'm very confident in the way things are going. And really looking forward to tomorrow."
Woods was 21 when he won his first Masters in 1997. Spieth would be the youngest major champion since Tom Creavy, who was a few months younger than Spieth when he won the 1931 PGA Championship.
But there's a lot of traffic on the road to a green jacket, mostly because of Watson.
He stretched his lead to five shots with a 7-iron to 6 feet for eagle on the second hold. He made only one birdie the rest of the way, a round sprinkled with putts that he either rammed too hard or left woefully short. Even so, the former Masters champion was right where he wanted to be.
"If somebody told me I would have shot 2 over and still be tied for the lead, I would have taken it in a heartbeat," Watson said. "So I got a shot on Sunday."
So do so many others.
Matt Kuchar, who squandered chances to win in each of the last two weeks, hit a pitch from well behind the 15th green that had to be perfect and was, setting up the best of his six birdies in a round of 68. Kuchar, a favorite in these parts from his days at Georgia Tech, was one shot behind along with Masters rookie Jonas Blixt, who fell out of the lead with a bogey on the 17th and shot 71.
Sunday's tee times
8:10 a.m. • Larry Mize
8:20 a.m. • Stephen Gallacher, Joost Luiten
8:30 a.m. • Mike Weir, Brandt Snedeker
8:40 a.m. • K.J. Choi, Sandy Lyle
8:50 a.m. • Francesco Molinari, Nick Watney
9:00 a.m. • Brendon de Jonge, a•Oliver Goss
9:10 a.m. • Thongchai Jaidee, Thorbjorn Olesen
9:20 a.m. • Lucas Glover, Billy Horschel
9:30 a.m. • Darren Clarke, Stewart Cink
9:50 a.m. • Vijay Singh, Jose Maria Olazabal
10 a.m. • Steven Bowditch, Hunter Mahan
10:10 a.m. • Martin Kaymer, Bill Haas
10:20 a.m. • Louis Oosthuizen, Jamie Donaldson
10:30 a.m. • Bernhard Langer, Henrik Stenson
10:40 a.m. • Jimmy Walker, Rory McIlroy
10:50 a.m. • Gonzalo Fernandez•Castano, Russell Henley
11:00 a.m. • Chris Kirk, Steve Stricker
11:10 a.m. • Adam Scott, Jason Day
11:30 a.m. • Ian Poulter, Kevin Streelman
11:40 a.m. • John Senden, Gary Woodland
11:50 a.m. • Kevin Stadler, Fred Couples
Noon • Thomas Bjorn, Justin Rose
12:10 p.m. • Lee Westwood, Jim Furyk
12:20 p.m. • Miguel Angel Jimenez, Rickie Fowler
12:30 p.m. • Matt Kuchar, Jonas Blixt
12:40 p.m. • Jordan Spieth, Bubba Watson