"I thought two under would be a good score," Spieth said. "Obviously I would have liked to finish the round a little better, but it could have been worse."
Justin Rose birdied five of the last six holes for a 67 that got him into the final group with Spieth tomorrow. Rose was at 204 overall, and three-time Masters champion Phil Mickelson was another stroke behind after shooting 67.
Spieth joined Tiger Woods as the only players in Masters history to get to 18 under with a birdie putt at the 16th hole, giving him a seven-stroke lead - his biggest yet.
Then he showed he's human.
Spieth's drive at the 17th wound up in the trees, and his second shot came up short of the green. He flubbed a chip, barely making the green, and then three-putted for the double bogey.
He also messed up his approach at the final hole, the ball sailing into the gallery behind the green. With a bunker in his way and not much green to work with, Spieth hit a dazzling shot that left a 10-footer to save par and set the record. He calmly rolled it in - not a shoe-in for the final round, but still firmly in control of the tournament.
"To see any putt go in on 18 is nice," he said. "It was really big. It was huge. It's one of the bigger putts I've ever hit."
For the second year in a row, Spieth will be in the final group on the last day.
He had a two-shot lead early in the round last year but faded down the stretch, finishing as a runner-up behind Bubba Watson.
This year, it's essentially a four-man game going to the last round.
Charley Hoffman (71) is the only other player with a single-digit deficit. He's six shots back.
The group at 210 includes Tiger Woods and Rory McIlroy, who both shot 68s.
- AAP