A mesmerising six-wicket haul from Pat Cummins put Australia in a commanding position against South Africa on Day 2 of the World Test Championship final – but the captain will need to produce similar heroics in the second innings after a horror batting collapse turned the decider on its head.

After a dramatic 14-wicket opening day, a further 13 fell as the world’s two best Test teams in the last two years took turns capitulating in the face of inspired pace bowling, as the decider continues to rocket along at a spectacular pace.

As it stands, Australia hold a 218-run lead with two wickets remaining, with a score of 8/144 at stumps – with batting treacherous throughout the first two days, it may prove a match-winning advantage already, especially given the Proteas’ feeble batting order and the brilliance of Cummins.

The champion quick, whose 6/28 are the best figures by a Test captain at Lord’s, produced a masterclass to rip through the Proteas’ middle and lower order, a score of 138 by the underdogs giving Australia a 74-run first innings lead.

He’d take all five of the wickets to fall to bowlers – the only exception to his dominance a disastrous run out surely borne of tailenders Keshav Maharaj and Kagiso Rabada being reluctant to face the champion quick in the next over.

But while his good form wasn’t quite undone in the second part of the day, once again Australia’s fragile batting order proved unable to deal with the Proteas’ pace attack, slumping to 7/73 before a gritty half-century stand from Alex Carey and Mitchell Starc prevented the complete rout that looked imminent.

Rabada once again winkled out Usman Khawaja (6) and Cameron Green (0) in the same over; Marnus Labuschagne again mustered only a middling total before edging Marco Jansen behind; but unpleasantly, their failures were joined by first-innings heroes Steve Smith and Beau Webster, both trapped LBW by third quick Lungi Ngidi.

In the end, the difference may come down to the Proteas’ alarming propensity of no-balls – with nine in just 40 overs on Day 2 to go with 10 on Day 1, they have already overstepped the mark 17 more times than their antipodean counterparts, a crucial distinction in a match where runs have proved nightmarishly hard to come by otherwise.

But whether or not Australia do retain their World Test crown, serious questions must be asked of the team’s badly misfiring batting order, of which perhaps only Smith has emerged from a chaotic first two days at Lord’s with reputation enhanced.

Considering the carnage that was to come, Day 2 began sedately, with Temba Bavuma and David Bedingham keen to dig in from an overnight total of 4/43.

With a pair of sparkling lofted drives off Starc, Bavuma in particular was looking in fine touch, the Proteas captain benefitting from an unusual successful LBW review that determined, to the batter’s surprise as much as anyone’s, that he had got a faint inside edge to Josh Hazlewood’s nip-backer down the Lord’s slope.

At 4/94, with the partnership having reached 64, South Africa’s morning seemed secure: enter Cummins.

Helped in securing the breakthrough by an excellent diving catch from Labuschagne at cover, Bavuma’s dismissal for 36 brought an end to the Proteas’ bright start.

Though Bedingham and Kyle Verreynne gritted their way through to lunch – though not without incident, with Bedingham surviving a controversial ‘handled ball’ shout after reaching for a ball inside-edged into his pads that was deemed dead by the umpires – the second session would belong to Cummins.

Verreynne was the first to fall, trapped in front by Cummins and watching in horror as Australia successfully challenged the on-field not out call; just three balls later, Jansen chipped a return catch to the captain for his fourth.

Wicket number five, and a spot on the Lord’s honours board alongside Rabada’s Day 1 haul, wasn’t far away, Bedingham’s resistance ending on 45 with a faint edge snaffled by Carey.

Doing damage both in the wickets column and to Protean bodies, Rabada found himself at the mercy of a Cummins bumper barrage, his shoulder and helmet copping the brunt of the assault.

Perhaps that explains the run out that soon followed: with Keshav Maharaj seeking a non-existent second run to remain on strike for Starc, a Travis Head throw from behind square reached Carey’s gloves quickly enough to beat the spinner home.

Fittingly, a Cummins bouncer would end the innings – and secure him a 300th Test wicket – Rabada choosing fight over flight and taking on a pull shot, only to find a diving Webster in the deep.

From 4/94, the final six Proteas wickets fell for just 44, all but the run out to Cummins.

A lead of 74, though, did little to assist Australia’s top order against a Rabada out for revenge from his travails with the bat.

Khawaja avoided a dreaded pair but did little else, feathering an edge behind off the star seamer; in a near mirror image of the first innings, Green lasted just three balls before edging Rabada into the cordon in the same over, the only difference a duck in the second innings compared to 4 on Day 1.

Looking more fluent, albeit hardly scoring any quicker, than in the first innings, Labuschagne again succumbed in familiar fashion for a score unlikely to remove doubts over his place in the team – and if 22 didn’t silence the critics, another edge behind off left-armer Jansen certainly won’t.

But Smith always loomed as the big fish, and after looking comfortably the weakest of the Proteas’ bowlers on Day 1, it was naturally Ngidi who struck the most telling blow.

Having once again started in commanding fashion, with a glorious straight drive signalling his intent from early on, Smith uncharacteristically missed an attempted flick off his pads on 13.

A review was always going to be forthcoming given the prize at stake; to Smith’s shock, ball-tracker found he had been hit in line with off stump, a positive call on hitting the stumps as well bringing the Proteas their most celebrated wicket of the innings.

4/48 with their best batter back in the pavilion, things soon got even more dire for Australia: Webster followed Smith in being trapped LBW by Ngidi to an identical delivery that could have landed his wicket on Day 1 had Bavuma sent it upstairs, while Head was castled off his pads by a Wiaan Mulder nip-backer.

When Cummins, looking to bring the fight to the Proteas quicks, was likewise castled for Ngidi’s third, Australia were 7/73, and with a lead of just 147, their hold on the match was slipping fast.

But after a nightmare Day 1 that featured a horror dropped catch and an unsuccessful reverse-sweep that sparked a lower-order collapse, Carey’s latest crucial late hand tilted the scales back the Aussies’ way.

With five boundaries in a brisk but steady 43-ball 50, the wicketkeeper, together with Starc, put on 61 priceless runs to blunt the Proteas’ attack, and take the lead past 200.

Lady luck, though, also played its hand: no less than five times in a dramatic final hour did Starc and Carey edges fall just short of South Africa’s impenetrable slips cordon, with both faint touches and healthy nicks all finding the Lord’s turf first.

Carey also found himself reprieved after being given out LBW in similar fashion to Bavuma earlier, with a review finding an inside edge so faint that surely even he didn’t realise was there.

Rabada, though, would end the wicketkeeper’s fighting hand on 43, trapping Carey in front for an LBW that not even the DRS could overturn, leaving Lyon and Starc the better part of two overs to see out the day’s play.

They did – but only just.

In a fitting climax to the day, each edge falling short had seen the Proteas’ cordon move closer and closer in, with Aiden Markram even donning a helmet to stand as near the bat as humanly possible – and in the end, they would pay a heavy price.

With just three balls remaining for the day, Mulder found shape away to catch Starc’s outside edge – only for this one, unlike the rest, to safely carry to a regulation gully.

Except Jansen, like the rest of the cordon, had crept too close, turning the catch into a reflex offering that he could only parry and, unlike his Day 1 catch of Smith, grass.

With Starc on 16 at stumps, and a history of critical tailend hands to bail Australia out, it may be the moment that costs South Africa Test Championship glory – but only time will tell.