Paul Casey produced a brilliant fightback to remain in contention for a first major title as former champion Rory McIlroy missed the cut in the US Open for the second year running.
Casey recovered from a triple-bogey on his fifth hole of the day to add a 71 to his opening 66 at Erin Hills and set the clubhouse target on seven under.
And, although McIlroy also recorded a 71 thanks to four birdies in his last six holes, the damage had already been done by a 78 on Thursday, when a record 44 players had broken par in the benign conditions.
Casey's opening 66 had left him a shot off the pace and he swiftly joined Rickie Fowler in the lead with a birdie from close range on the 11th, his second hole of the day, only to bogey the next and run up a triple-bogey on the 14th.
The 39-year-old was only able to move his fourth shot a matter of inches in heavy rough over the back of the green on the par five, before hacking out sideways and taking three putts from just off the green.
However, after dropping another shot on the 15th, Casey regained his composure superbly to birdie the 17th and 18th, the latter being the second longest hole in major history at 676 yards.
And the former Ryder Cup player then made it five birdies in succession - just one short of the US Open record equalled by Adam Hadwin on Thursday - by picking up shots on the first, second and third.
"I lost a bit of skin out there," Casey said of the triple bogey. "I got out of position but it's the attitude, it's the grit that matters at the end of the week."
McIlroy's pre-tournament comments proved disappointingly accurate after he had predicted that anyone who could not hit the wide fairways "might as well pack your bags and go home.''
The world number two hit just five of them to tie for last in the 156-man field in that category on day one, but still made four bogeys on Friday despite hitting 11 of 14 fairways.
"I showed up for the last six holes at least," joked McIlroy, who was three over par after 12 holes before carding birdies on the fourth, fifth, seventh and ninth.
"I definitely hit it better off the tee and gave myself a lot more looks at birdie but at the end of the day I need competitive rounds with a card in my hand and I've been light on those this year.
"I saw some positives on the back nine to take into next week and, even though this is disappointing, the last two rounds will serve me well in this busy summer.
"I started to let it go towards the end and show what I can do. (On Thursday) I was a little anxious and that caught up with me as the round went on. Hopefully I've got a lot of the bad stuff out of my system and it's just a matter of getting competitive rounds under my belt."
McIlroy won the US Open with a record 16-under-par total in 2011, but was a combined 50 over par for his seven other appearances before this week and missed the cut at Oakmont last year following rounds of 77 and 71.
The 28-year-old needed to make a fast start on Friday to avoid another early exit, but missed from five feet for birdie on the 10th - his opening hole - and 12 feet on the 11th, before a poor chip from the back of the 12th green led to a bogey.
Playing just his seventh tournament of the year due to a rib injury, McIlroy bounced back with a birdie from 12 feet on the 13th, but carded a hat-trick of birdies from the first before his encouraging late rally.
At five over par, McIlroy was four shots outside the projected cut mark, while playing partner and former world number on Jason Day finished nine over following a 75.
Casey has recorded three consecutive top-six finishes in the Masters, but has just one top-10 in the US Open in 13 attempts, which came a decade ago at Oakmont.
"It feels good," the 39-year-old said. "Not every day you enjoy a round of golf with an eight on the card, but I'm a pretty happy man.
"It was a good display, all my own fault, but a good display of what can happen if you get out of position on this golf course. Even just trying to take my medicine is very, very difficult. It's a good eight in the end.
"I had been swinging it well and it felt really, really good a couple holes later to be picking the ball out of the hole for a birdie. Then clawed all the way back and actually picked up one more to the good by the time we were finished."
Asked if he would have been able to recover from such a mistake earlier in his career, Casey added: "In my good seasons, yes, but there have been times when I struggled, so probably not!
"I was upset with the score I had made, but it did not have any effect on my attitude or how I was going to then approach the rest of the round or the next shot. Part of that is just age and part I'll give credit to Johnny McLaren (his caddie), credit to my wife and my little boy."