Justin Rose has seen his hopes of a second major title in the space of two months suffer a potentially fatal blow as Oak Hill finally bared its teeth in the US PGA Championship.
But Lee Westwood and defending champion Rory McIlroy were right back in contention as halfway leader Jason Dufner also fell foul of a tough opening stretch in the final major of the year.
Rose began the third round three shots off the lead and looking to join golfing legends Gene Sarazen (1922), Ben Hogan (1948), Jack Nicklaus (1980) and Tiger Woods (2000) as the only men to win the US Open and US PGA in the same year.
But the 33-year-old Englishman dropped six shots in the space of four holes to plummet down the leaderboard, making a bogey at the second and a double bogey on the third after missing the green off the tee and then three-putting.
Rose, winner of the US Open at Merion in June, dropped another shot at the par-five fourth and then saw his approach to the fifth spin back into the water to cost him two more shots.
At level par he was nine shots off the pace until Dufner, who had equalled the lowest score in major history with a 63 yesterday, also took six on the fifth after driving into a water hazard.
That brought a number of players right back into contention, including Westwood who had dropped three shots in the last two holes of his second round 73 to start the day eight off the lead.
Westwood, still seeking a first major title at the 63rd attempt after letting a two-shot lead slip going into the final round of the Open, carded three birdies and one bogey to reach the turn in 33.
The 40-year-old then dropped a shot at the 11th but birdied the 12th and 14th to improve to four under and within three shots of the lead.
McIlroy had been heading for a second consecutive missed cut in major championships when he stood five over for 11 holes of his second round on Friday, but the former world number one birdied four of the next six to finish level par.
He was still level for the tournament after 12 holes but birdied the 13th, holed from 50ft for another on the 17th and then chipped in on the 18th to card a 67 and set the clubhouse target on three under.