Tiger Woods has given up the outright lead at the PGA Championship, three-putting the 18th green to be one of three players on four under at the halfway stage of the tournament, while Australia's Aaron Baddeley and Adam Scott are tied for seventh.
Woods shot a one-under 71 in the second round to sit alongside Fiji's Vijay Singh and Carl Pettersson of Sweden at the top of the leaderboard with Baddeley and Scott three shots back.
After scoring birdies on the 16th and 17th holes on Friday to move to three under, Baddeley ruined that good work with a double-bogey on the 18th to complete a three-over 75.
Scott, who started his round on the back nine, also shot 75, finishing his second round with bogeys on the 7th and 9th holes and is set to play alongside Baddeley in Saturday's third round.
Geoff Ogilvy endured a tough day with his 78 dropping him down to two over and a tie for 24th alongside fellow Australians Marc Leishman and Greg Chalmers.
After two birdies in the first four holes at Kiawah Island on Friday, Woods was at five under and despite dropping a shot on the 8th, the world No.2 was cruising after another birdie on the 12th.
A run of five par scores followed and Woods had the chance to move to six under and a two-stroke lead on the 18th green before three-putting for a terrible end to his second round.
Singh carded a three-under 69, the best score of the round, to move up 31 spots to the top of the leaderboard, while Pettersson had a tough second day in South Carolina, shooting a two-over 74.
Woods, Pettersson and Singh have a one-stroke lead over Ian Poulter of England, who bogeyed the final hole to give up a share of the lead.
Jamie Donaldson of Wales and world No.3 Rory McIlroy are a further shot back on two under, while Baddeley and Scott head a group of four players on one under.
With the cut set at six over, US Open champion Webb Simpson was one of the highest-profile players to miss out on the weekend's action, while Aussies Robert Allenby (+7), Jason Day (+8) and Brendan Jones (+10) were also eliminated.