The 25-year-old American, who has won four of his past eight starts, eagled the par-5 10th at Southern Hills but made bogeys on five of the last 10 holes to fall well back of 18-hole leader Rory McIlroy.
"I'm definitely a lot further back than I had hoped to be," Scheffler said.
"It's early in the week. Still a lot of golf left to play. Six shots over three days really isn't that big of a deal."
It's only that close because Scheffler, after finding water off the tee, made a 16-foot putt at 18 to save par and avoid three bogeys to finish the day.
"It's definitely going to make my dinner taste a little better," Scheffler said. "Bogeying the last three is definitely not very fun, so it was good to make that par at the end.
"I'm still pretty frustrated with how I played the back nine, but overall one-over par playing as poorly as I did today -- I didn't shoot myself out of the tournament, so I'm still in OK position."
Scheffler fared the best out of a group that featured the world's top three players.
Second-ranked Spaniard Jon Rahm, the 2021 US Open winner, shot 73 while third-ranked American Collin Morikawa, reigning British Open champion, had only one birdie in shooting 72.
"Definitely got windier as the day went on. The greens get a little bit more chewed up," Scheffler said. "That's what happens when you play late in the day. Today was windy so the course was challenging. I didn't keep myself in position on the back nine and paid the price for it."
Scheffler said he had no complaints with the setup, just minor issues with pebbles in the abundant bunkers.
"With there being so many around the green you really kind of need a good lie how fast the greens are," he said. "I shouldn't be in too many bunkers and I put myself in them."
Scheffler's big moment was his 10-foot eagle putt at the par-5 fifth.
"I hit two fantastic golf shots," he said. "I held a driver against the wind off the tee and then I drew a 3-wood in there and I ran it up kind of the front part of the green.
It was two just great shots, especially the 3-wood, and then a great putt."
This article was translated from the original in French. Agence France-Presse website