Troy Merritt saw the quality players on the leaderboard behind him and kept pushing for one more birdie, and then another.
When his final putt fell, a birdie on the 18th hole, Merritt learned for the first time that his 10-under-par 61 matched a course record at Harbour Town Golf Links. He is 12 under, good for a four-shot lead after 36 holes at the RBC Heritage Presented by Boeing.
Merritt upstaged Jordan Spieth's 62, which launched the Masters champion into contention.
"Anytime you match shot for shot with the Masters champ, with the way he's playing, it's a pretty good feeling," Merritt said.
In contrast to Merritt's blitz during a calm afternoon off of Calibogue Sound, Spieth's charge drew a crowd.
The 21-year-old strolled through the crushing gallery behind the ninth green after his round, promising autograph seekers he would return after he signed his scorecard.
Patience was also Spieth's message after stumbling with a 74 on Thursday.
He turned away whispers of a Masters hangover with nine birdies and no bogeys Friday on a red-letter day for scoring.
The round matched Spieth's best as a professional, though one off the number of Merritt and David Frost, who fired a 61 in the second round in 1994.
Merritt is four clear of 2014 champion Matt Kuchar. Spieth is 6-under for the tournament, within range after his first round left everyone wondering if the talk-show circuit and major triumph fried his golf brain.
He promised after his opening round that fatigue was no excuse for his play and that he wanted to compete. If there were doubters then, they disappeared as his name joined the leaders.
"And now I've got myself probably some rest tomorrow, which is nice," said Spieth, who said a change in ball position on the range helped fuel his round. He won't tee off until 1:25 p.m. "I have a later tee time, so (I'll) probably get a little extra sleep."
Kuchar, playing with Spieth, finished with a 6-under 66 following a couple of par saves on the final two holes as Spieth-mania bubbled over. Kuchar pointed out to caddie Lance Bennett on the eighth hole how deep the fans extended beyond the ropes.
He and Spieth enjoyed each other's company. Spieth made fun of Kuchar's relative old age, and the 36-year-old responded with his own jabs.
To get an idea of Spieth's magnetism this week, consider that the defending champion and then-leader Kuchar fielded a majority of questions about his young playing partner.
"I was concerned watching yesterday that he might not be around for the weekend," Kuchar said. "What a draw he is, and now to have him right in contention is awesome."
Spieth, starting on No. 10 with an early tee time, went out in 31. He birdied his final two holes, chipping in on No. 8 to a huge roar and sticking his pitch on the par-4 ninth for another birdie.
The sea of spectators crammed between the ninth green and putting green parted as Spieth made his way to sign his scorecard. The mania gets to continue two more days.
"I don't want to go home early," Spieth said.
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