Tiger Woods found the second round harder going in his return to action at the WGC-Bridgestone Invitational.
The former world number one followed up his opening 68 with a round of 71 to slip to one under for the tournament.
Overnight leader Adam Scott could not match his first round of 62 and remains tied for the lead in a group of four players on eight under.
Scotland's Martin Laird was a shot back at seven under par after birdieing his last three holes for a 67.
"I came into this week feeling fresh and on a high," said Laird, who got married last Saturday in Colorado. "Sometimes it's amazing when you have no expectations how well you'll play."
Scott hit a level-par 70 and was caught by two of the early movers on day two at the Firestone Country Club, Americans Ricky Fowler (64) and Ryan Moore (66), who joined the Australian on eight under.
Keegan Bradley of the United States hit a fine 65 to move alongside the leaders, but Australia's Jason Day failed to make it a group of five when he bogeyed the 18th to end the day of seven under with Laird and Sweden's Robert Karlsson.
World number two Lee Westwood looked set to challenge at six under but four bogeys in the last six holes saw him slip to two under.
Open champion Darren Clarke, playing alongside Woods, could only manage a 74 and finished on a humbling 11 over after two rounds, while fellow Northern Irishman Rory McIlroy carded a second 68 to go four under par, one clear of world number one Luke Donald (69).
Woods - a seven-time winner at Firestone - was playing for the first time in 12 weeks after injury.
He made four birdies to three bogeys, but a double-bogey six on the sixth hole cost him dear, although he took comfort from what he felt was a second strong day in terms of driving.
"I didn't putt as well as I did yesterday, and consequently I just never got the round going," said the 14-times major champion.
"I know my stats don't show it, but just the way I'm driving the golf ball - I'm so close to putting the ball on a string, so it's coming."
He added: "I got so much more compression and the ball is just going. I've just got to get used to that and trust the number. I'm hitting the ball numbers I've never hit before."