Rory McIlroy holds largest Masters lead ever through 36 holes after 9-birdie round

Rory McIlroy waves to the gallery after his putt on the 13th hole during the second round of the Masters on Friday. (Matt Slocum / Associated Press) Among the many rules at Augusta National — no cell phones, no booing, no lying in the grass — patrons are not allowed to run. Somebody tell Rory McIlroy.

The defending Masters champion was sprinting away from the field Friday, building a six-shot lead heading into the weekend and putting himself in prime position to become the first repeat winner since Tiger Woods in 2002. McIlroy atoned for two bogeys with nine birdies, shooting a seven-under-par 65 to improve on his stellar 67 in the opening round. “When I was standing on the 12th tee, I didn’t imagine that I would be six ahead going into the weekend,” said McIlroy, who birdied six of the final seven holes.

Read more: Tiger Woods is back in the rough. How a dependence on painkillers took down a golf great He now holds the largest 36-hole lead in Masters history. And he completed that masterpiece in the afternoon, when the legendary course was even firmer and more slippery than it was in the morning.

The warm weather and cloudless skies set the stage for a test of surgical precision in the final two rounds. “These greens are going to be concrete,” said Wyndham Clark, who followed an even-par round with a four-under 68. “Obviously getting really fast without the wind, so it’s going to really matter hitting it in the fairway and the angles, and being patient.