Australia's bowlers have taken a huge stride towards winning the first Test against West Indies in Perth, dismissing the tourists for 283, then reaching 1-29 at the close of the third day, a lead of 344.
Against a West Indies team desperately knuckling down in an attempt to save the match, a brilliant burst of 6-39 in 18.2 overs with the second new ball did the damage, with Mitch Starc the ringleader with a devastating spell.
Usman Khawaja (6) fell to Alzarri Joseph before the close, but David Warner (17) and Marnus Labuschagne (3) comfortably survived, set to pile on more runs on day four.
With two days left, a victory for the West Indies is no longer a realistic option, with a draw their best and only hope.
The only question for Australia, having not enforced the follow on, will be when to declare to give themselves enough time to bowl the tourists out and take a 1-0 lead in the series.
West Indies may have started the day with some hope of batting long.
After a promising evening on day two, debutant Tagenarine Chanderpaul (51) only added four more runs to his overnight score.
That got him to his first Test half-century, but he suffered his first Test dismissal the next ball when he edged Josh Hazlewood to David Warner at first slip.
That meant he fell short of the 62 scored by his famous father, Shivnarine, on his Test debut back in 1994, but current West Indies captain Kraigg Brathwaite managed to eclipse that mark. Just.
He only went two runs beyond it before he became Cummins's 200th Test wicket, bowled through the gate.
Kyle Mayers (1) almost gloved Cummins's next ball to Alex Carey, but only survived seven more deliveries before Starc found his off stump through the gate.
There was concern for number three Nkrumah Bonner who made 11 off 26 balls before being struck hard on the helmet from a Cameron Green bouncer.
Bonner played out another half hour for 20 balls until drinks, but then slowly walked from the field after feeling dizzy, retiring hurt for 16.
The Australian bowlers did not embark on a sustained bumper barrage, but were vicious when they did use the short ball, regularly rapping Jermaine Blackwood (36) on the gloves and body.
Local boy Green was the chief enforcer, striking Jason Holder flush on his helmet shortly before tea.
Holder (27), who was given a reprieve when DRS overturned a strong LBW shout earlier in his innings, fell the every next over, clipping Nathan Lyon to David Warner at leg slip just three balls after launching him over long on for six.
Shamarh Brooks (33) came next in as concussion replacement for Bonner and immediately went to work, scoring at a good rate and keeping good balls out with regularity.
He made it to tea alongside Blackwood, but the second new ball came out shortly after the break and Starc made it sing, getting Blackwood LBW and bowling Joshua da Silva (0) through the gate with hooping in-swingers; at one point taking 2-0 in four balls.
Roston Chase went for 13, becoming Cummins' 201st victim after falling LBW to a ball that nipped back and onto his pads.
Kemar Roach did not last long, falling for a duck after Smith took a superb grab at first slip off the bowling of Lyon, before Alzarri Joseph was caught by Warner after skying a Green delivery.
Warner raced off the ground after completing the catch, betraying Australia's plan to not enforce the follow on, and made 17 off 26, while weathering a venomous spell from Joseph.
Khawaja was out for 6, caught behind off a ball from Roach that left him off the seam — further evidence that the pitch was getting harder to bat on as time goes on.
But Labuschagne (3) remains, set to add more runs and set up a victory push on day four.
