Viktor Hovland slipped down the leaderboard at the WGC-Workday Championship after being unable to build on a blistering start in Florida.
The Norweigan posted five consecutive birdies in his first six holes at The Concession Club, with back-to-back gains from the seventh taking him to seven under for the day and briefly within two of the lead.
Hovland then racked up an ugly quadruple-bogey at the par-four ninth - his final hole - after hacking out of the bushes into the bunker and then thinning his next shot to an unplayable lie, with a three-under 69 seeing him head into the weekend seven strokes behind leader Brooks Koepka.
"I mean I felt like I did a good job of going through my options and not really stressing too much," Hovland told Sky Sports. "The one brain fart there was that I tried to play the hero shot from the lip of the bunker.
"I hit a terrible shot and the second shot is where all the trouble starts. I just need to catch it a little bit cleaner and hit it on the green, then I'd shoot 65. It's just small margins."
Bryson DeChambeau is a further stroke off the pace despite posting a score 13 shots better than the opening day, with the US Open bouncing back from an opening-round 77 to match Collin Morikawa's joint-low round-of-the-day 64.
"It's just a tale of golf, you can have both ends of the stick," DeChambeau said. "I didn't play terrible yesterday, I just didn't get anything going my way, especially on that back nine. Had some bad mistakes and that's what happened.
"I definitely didn't feel like I shot 5 over yesterday. I knew coming into this today just keep your head down and keep going in the right direction, try to keep going in the right direction making the same swing a
"It was a lot of perseverance, my caddie kept me strong and we just kept plodding along and making some great putts out there."
Watch the WGC-Workday Championship throughout the weekend live on Sky Sports. Live coverage continues on Saturday with Featured Groups from 1pm, ahead of full live coverage from 5pm.