England ended day four of the second Ashes Test at Lord's on 96/4 - a lead of 104 - but events were dominated by the bouncer to Australia's Steve Smith.
England v Australia second Test scorecard - Australia trail by 8 runs
England 1st inns: 258 all out (Burns 53, Bairstow 52; Hazlewood 3-58, Cummins 3-61, Lyon 3-68)
England 2nd inns: 96/4 (Stokes 16 no, Buttler 10 no; Cummins 2-16, Siddle 2-19)
Australia 1st Inns: 250 all out (Smith 92; Broad 4-66, Woakes 3-61)
Steve Smith's titanic tussle with Jofra Archer, and the 92mph bouncer that ended their battle in gruesome fashion, dominated the fourth day of a second Ashes Test that is destined for a tense conclusion.
England lost their top order cheaply in the evening session and will begin day five 104 runs ahead on 96 for four, but events at Lord's will be remembered for an unforgettable, adrenaline-fuelled duel in the afternoon.
Smith was on 80 and progressing towards his third successive century when debutant Archer clattered him in the neck at express pace, brutally flooring the Australian.
The England quick had already struck another nasty blow on Smith's left forearm during a compelling spell that saw him clock one lightning fast delivery at 96.1mph, showcasing the sport at its most visceral, vital and ultimately violent.
Smith was led from the field but returned just 40 minutes later after passing concussion tests, dismissed softly by Chris Woakes for 92 and looking understandably shaken.
Archer will not take any pleasure in the plight of his Rajasthan Royals team-mate, but if there were any remaining doubts about the 24-year-old's ability to become one of the most ferocious Test bowlers around - remember Australia coach Justin Langer's comments about the longer format wearing him down - they evaporated at the home of cricket.
The morning session did little to hint at the drama to come, with Australia adding 75 runs for the loss of a solitary wicket to reach 155 for five.
Stuart Broad predicted England would need to bowl their opponents out before lunch to have a realistic hope of winning and, although he had Matthew Wade well caught by Burns at slip, they fell well short.
Smith batted with his usual idiosyncracies throughout the first session, pirouetting, pivoting and pointing his bat after almost every delivery and blunting the English attack for two hours on his way to 50.
Archer was visibly revved up after the break, setting Tim Paine up with a bouncer in his first over of the afternoon then drawing a bat-pad catch. Buoyed by the crowd he cranked it up past 90mph and kept his foot on the gas as he embarked in an unforgettable spell that required an adversary of Smith's class to elevate it.
Archer was into his 24th over of the innings when he finally busted through Smith's defences in a meaningful way, digging one in and thumping hard into the left forearm. He winced in pain, pausing for treatment and popping a painkiller to dull the ache as the physio applied a protective pad and compression bandage.
He initially struggled to grip the bat but was not about to admit defeat and when Archer started his next over, he gamely took on two more rapid, back-to-back bouncers. The first sailed off the top edge and over the wicketkeeper for four and the second trickled towards fine leg after another mis-hit.
Smith, so long the controlling, dominant figure in the series, was beginning to feel out of his depth and the whole ground knew it. The next ball at Smith was Archer's fastest yet on the international stage, clocking in a blood-curdling 96.1mph as it reared towards the ribcage.
Attempting to protect both body and wicket Smith somehow forced it down off his gloves, grounding just in front of short-leg when a catch probably seemed the likelier outcome.
Smith momentarily grabbed back the upper hand at the start of the 77th over, getting on top of the bounce as his rival banged another one in and hooking cleanly for four to reach 80. The response arrived within a matter of seconds and was devastating.
It was another bouncer, zipping in at 92.4mph and too straight to easily avoid. Smith got into an awkward position, turning his head as the inevitable impact approached.
He tumbled face first to the ground, flicking off his helmet before rolling over and facing the sky. The impact was brutal and Smith's subsequent stillness as medics from both teams dashed out truly concerning.
It was hard not to remember the fate of Smith's friend Phil Hughes, killed after being hit by a bouncer while playing state cricket for South Australia five years ago, but thankfully the news from the middle was positive.
Smith was persuaded, somewhat reluctantly, to pause his innings but was back after 54 balls. Whether he should have been encouraged not to is a different matter, an uncharacteristically tame lbw to Chris Woakes followed by a moment of apparent confusion as he simultaneously walked off and signalled for DRS.
Australia wrapped up eight behind on 250, Jack Leach and Broad (four for 65) finishing things off.
Pat Cummins wasted no time turning the screw after the changeover, removing Jason Roy and Joe Root in successive balls in his third over. The former managed just two and has now scored just 45 in five innings as an opener while Root nicked off for his first golden duck in 153 Test innings.
Peter Siddle kept the pressure by picking off two more of the top four, Joe Denly caught and bowled for a chancey 26 and Burns edging to Paine for 29.
England might have crumbled had any of three Ben Stokes edges in a single Nathan Lyon over been held, with the all-rounder also benefiting from one of two sound lbw appeals that should have been reviewed.
Day four reaction
Australia coach Justin Langer admitted the ferocious blow to the neck which felled Steve Smith at Lord's brought back "rough memories" for his side.
It was only five years ago that Smith's friend and team-mate Phil Hughes died after being hit on the neck by a bouncer during a Sheffield Shield game in Sydney, a harrowing incident for the whole of Australian cricket, not least current team members Nathan Lyon, Travis Head and David Warner, who played in the match.
Happily Smith was able to get up, retiring hurt but returning to action 40 minutes later before being dismissed for 92.
"You never like seeing your players get hit like that, no doubt, there's obviously some pretty rough memories of a blow like that so...there was no fun in it," said Langer, who also predicted that optional 'stem guards' on helmets might now become obligatory.
"Today was an ugly incident. I know (the extra protection) came in after the tragedy of Hughesy so I'm sure that will get talked about. At the moment, the players have a choice and I wouldn't be surprised if they become mandatory in the future.
"Thankfully Steve has come through okay. He got another 92 today, what an innings, what a player and what great courage as well, that he came back out."
There was widespread surprise that Smith opted to return to the middle when Peter Siddle was dismissed, but Cricket Australia allowed him to make the decision after he passed all on and off-field testing under the watch of team doctor Richard Saw.
Langer would have stepped in had he felt Smith was in danger of further serious injury but instead found himself marvelling at the player's desperation to get back out in pursuit of a Lord's hundred.
"These guys are like my sons, alright. You're never going to put them in harm's way. He was going 'mate, I just want to get out there. I can't get up on the honours board unless I'm out batting'.
"He was determined but he wouldn't have gone out there unless we thought it was OK. I asked him privately, I asked him behind closed doors, I asked him in front of the group."
Chris Woakes was the man who eventually dismissed a shaken Smith for 92, winning an unusually soft lbw.
He was in in awe of Archer's efforts in weakening Smith's control as he moved towards what would have been a third successive Ashes century.
"You want Ashes cricket played hard and tough but you don't wish injury on anyone, regardless of the situation of the game," said Woakes.
"It took a serious spell of bowling from Jofra to get Steve out of his bubble because so far this series he's been incredible. It was incredible to watch and thankfully, having seen Steve on the balcony, he seems OK. For him to come out having been hit the way he was does show some courage and character."
Woakes said Archer's bowling was the quickest spell he had witnessed on a cricket field.
"You see quick bowling around the world but that was a prolonged spell of fast bowling," he said.
"You could tell it was special, the crowd were certainly behind every ball. It was pretty special to be a part of. I haven't been on the field when someone has bowled that fast consistently."