Defending champion Hideki Matsuyama fell from 10 to 13 shots behind sole leader Justin Thomas and is tied for 36th place after the third round of the WGC-Bridgestone Invitational on Saturday.
After shooting rounds of 67 and 72 for an up-and-down start at the Firestone Country Club, Matsuyama struggled with four bogeys in the back nine, including the par-5 16th which he eagled on the opening day.
The world No. 16 had as many birdies in an even-par round of 70 but it was not enough to place him in the chasing pack, and the 26-year-old Japanese had no answer for his lack of distance control.
"I didn't feel uneasy hitting at any holes but the ball wouldn't stay in the fairway," said Matsuyama, who hit 10 of 18 greens in regulation.
"It's tough because I can't post good scores. Still, I'll keep trying tomorrow," he said.
Thomas, who was one of three joint leaders after round two, shot a 67 to bring his 54-hole total to a 14-under 196. The American takes a three-stroke lead over Rory McIlroy and Ian Poulter into Sunday and will be aiming for his third victory of the season.
Elsewhere for Japan, Ryuko Tokimatsu is 43rd at even-par 210, Satoshi Kodaira sits 61st with a score of 3-over 213 and Kodai Ichihara is bottom of the leaderboard with a 15-over 225 total.