Paul Casey entered what is reverently referred to as "the zone" on Friday afternoon at the Byron Nelson Championship.
After a front nine in which he shot a 1-over 36, Casey made six birdies and an eagle on the back nine for a 27.
Here's a look at his card:
"I had no concept of what I was doing," Casey said.
He also said it was the best nine holes he has ever played.
"I like to think I would be pretty good at shooting low rounds of golf through the past," Casey said, "but certainly nothing like that."
Paul Casey on whether he's ever shot 27 for nine holes before: "On par-3 courses, I think."— Jason Sobel (@JasonSobelGC) May 16, 2014
It's the eighth time a 27 has been shot on the PGA Tour and was just one off Corey Pavin's record of 26 for nine holes at the 2006 US Bank Championship in Milwaukee.
Casey is 6 under overall and near the top of the leaderboard.
Here's his actual card (that is a lot of threes):