The Associated Press

AUGUSTA, Ga. — Bryson DeChambeau believes science was at work late in the afternoon at Augusta National, creating a force in the atmosphere where big roars from great shots filter through the back nine.

An easier description: Another exciting finish at the Masters, this time on a Thursday.

Brooks Koepka got it started, adding to his reputation of playing his best golf in the majors. He rolled in a 20-foot birdie putt from behind the 12th green, the first of four straight birdies to take the lead. DeChambeau answered with four straight birdies at the end of his round, with two shots inches away from being even better.

His 8-iron on the par-3 16th grazed the edge of the cup. His 6-iron into the 18th was even better, so good that it rolled smack into the middle of the pin and bounced back an inch or two .

Both wound up in a share of the lead at 6-under 66.

“Absolutely, there is an energy and there is something in science that does talk about that,” said DeChambeau, who has a scientific answer for everything. “It’s great to have momentum and great atmosphere and gets you all pumped up, creates adrenaline flow. … I believe that’s partially what happened today.”

They were one shot ahead of Phil Mickelson, who delivered thrills of his own.

Mickelson found some momentum after shots in the pine trees at No. 10 and in the water on No. 11, both leading to bogey when he thought it could have been worse. He answered with three birdies on the next four holes, including a shot into the 16th that stopped inches from the cup.

He had a 67, his best start since 2010, when he won his third green jacket.

Tiger Woods missed all the action. He played earlier in the round and methodically scored a solid 70. It was a good start for Woods in his quest to end 11 years without a major, and he was atop the leaderboard briefly until a late bogey. He sounded satisfied.

“I’ve shot this number and won four coats, so hopefully, I can do it again,” said Woods, who slightly miscalculated. The last green jacket he won in 2005 began with a 74. The goal was to not fall too far behind early, and he is just four shots behind.

Rory McIlroy’s bid for the last leg of the career Grand Slam began with a 73, which featured six bogeys.

“I made five birdies — that wasn’t the problem,” McIlroy said. “I just made too many mistakes.”

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