Former champion Rory McIlroy's US Open campaign veered from the sublime to the ridiculous as Lee Westwood battled to remain in contention at Oakmont.
McIlroy completed his weather-delayed first round on Friday with bogeys on his last three holes to finish seven over par, equalling his worst score in the event which provided his first major victory in 2011.
The only good news for the 27-year-old was that Thursday's early starters were then told they would not start their second rounds until Saturday morning, after initially being given a start time of 8:54pm on Friday evening - two minutes after sunset.
The combination of a session on the range with coach Michael Bannon and a more aggressive approach then paid off for McIlroy on day three as he carded four birdies in his first seven holes.
Starting on the back nine, McIlroy birdied the 10th, 12th, 14th and 16th and then drove the green on the short par-four 17th, only to three-putt for par from 80 feet.
Further birdie chances went begging on the first and second before McIlroy's round imploded on the third, the world number three four-putting from around 10 feet to run up a double-bogey six.
At five over par McIlroy was nine shots off the lead shared by France's Gregory Bourdy and American Dustin Johnson and just a shot inside the projected halfway cut.
Johnson had completed rounds of 67 and 69 on Friday, while Bourdy started his second round with a bogey before firing birdies at the fifth, sixth and ninth and then holing out from 137 yards on the 11th for an eagle two.
Further birdies from close range on the 13th and 14th took Bourdy into the lead before he bogeyed the 16th to drop back to four under par.
Westwood had held the outright lead on five under after birdies on the first and fourth, but bogeys on five of the next six holes left the former world number one on level par alongside Louis Oosthuizen, who had earlier completed a superb 65.
Oosthuizen, who recovered from an opening 77 at Chambers Bay last year to finish joint second, birdied four holes in a row on his back nine on Friday and returned to the course on Saturday to par the eighth and birdie the ninth.
"I didn't have a great first round. I felt as uncomfortable over the golf ball as I have in a while," said the former Open champion, who lost a play-off at St Andrews last year.
"I couldn't really find anything on the range as well before the second round, but out on the golf course I found something in my set-up that felt comfortable, started getting my little cut back on my driver and went from there.
"I hit a few shots really close. I was building really nice momentum and then I had a horrible four-putt on 17 for bogey, which put all the brakes on, and then a bogey on one to go back to five over. But the last seven holes I went five under and just had good stretches of good putts, solid shots and giving myself opportunities.
"It was a great round. I could have easily just gone out there and shot another 74 or something and be out of the tournament. What I learned from last year was to never really give up in a US Open. Just grind on. If something happens then you can get yourself right back into it."