AUGUSTA, Ga. (AP) -- Jordan Spieth stepped up for one last putt, nothing more than a tap-in really.
Suddenly, he backed away.
This one was important. It meant history.
After taking his time, Spieth knocked in a short par putt on the 18th hole Friday to claim the 36-hole scoring record at the Masters, breaking a mark that has stood for nearly four decades.
Raymond Floyd reached the midway point of the 1976 Masters with a 131 on the way to an eight-stroke victory.
Spieth did him one better, posting a 14-under 130 that has included 15 birdies and only one bogey through the first two days.
"That's really cool," said Spieth, who shot a 6-under 66 on the heels of an opening 64. "It's cool anytime when you set a record, but to do it here is pretty awesome."
The 21-year-old Texan was blowing away everyone in the field except Charley Hoffman, and even he faced a rather daunting five-shot deficit after shooting 68.
Normally, Hoffman's 135 at the midway point would be good enough for the lead.
Not the way Spieth was playing.
"I feel really good this week," the leader said. "I'm not very nervous."
Spieth gave a glimpse of his enormous potential a year ago at Augusta, leading on the final day with a chance to become the youngest champion in Masters history. He faded down the stretch, settling for the runner-up spot behind Bubba Watson but leaving no doubt that golf had a budding new star.
Spieth arrived this year on top of his game, having won, finished second, and lost in a playoff in his last three events before the Masters.
"Last year and the momentum from the last few weeks, I've been kind of on my game and feeling really good about coming to a place that I love, that everybody loves," Spieth said. "It's special. It's special to be in the tournament, let alone out front."
Spieth had a 7-foot birdie try at the final hole for a 129. He misread the break and watched it slide past the left side of the cup on the slick Augusta greens.
He initially went up to tap it in, standing awkwardly so he wouldn't step in the line of playing partner Henrik Stenson, who still had a short putt of his own.
Then, Spieth backed away, marked his ball and waited for Stenson to finish before knocking his in for the record.
"I was a little outside the comfort zone," Spieth said. "I didn't want to force anything at that point. I'm going to make it if I step off. There's no point in letting anything else happen."
Spieth said his biggest goal on the weekend is to avoid watching the scoreboard.
He knows he's playing good enough to win. No need to worry about what others are doing.
"Keep my head down, just need to set a goal for myself," Spieth said. "Obviously Charley's playing great, and we may be pretty close up there, and who knows what can happen on the weekend here."
He expects the guys in the green jackets to really toughen up the greens and the pin placements on the weekend, not wanting anyone to dominate their course like Spieth has over the first two days.
"I'm sure they don't like seeing really low scores," said Spieth, who also tied the major championship record for lowest 36-hole total, matching three others.
Ernie Els, at 139, was the only other player with a single-digit deficit when Spieth finished his round. Everyone else was at least 10 shots behind.
"He's special," said Els, who began the day three shots back and fell farther behind with a 72 on a sultry, overcast day. "Nothing stands out, because he does everything well. He's going to be tough to beat."
On Thursday, Spieth posted the lowest opening round at the Masters in 19 years, just one stroke off the major championship scoring record. He came into Friday with a three-shot edge over Els, Hoffman, Justin Rose and Jason Day.
Now, Spieth is even farther ahead.
Not a time to relax, however.
"The weekend of a major, a round can seem like two rounds," Spieth said. "What's running through your head, the stress levels are higher. The hardest thing is putting aside wanting to win so bad. ... We're only at the halfway point. I'm aware of that. I don't want to get ahead of myself.”