A relentless Australia spearheaded by debutant Scott Boland skittled England for an embarrassing 68 on Tuesday to win the third Test by an innings and 14 runs and retain the Ashes with two matches still to play.

The tourists resumed in Melbourne on 31 for four, still 51 runs behind, after a disastrous final hour on Monday against some outstanding fast bowling that left their Ashes dreams in tatters.

Their survival rested on skipper Joe Root, but when he fell for 28, it was just a matter of time before the rest followed. 

Boland, called up as injury cover, was invincible on his home ground at the MCG, taking 6-7 off four overs, equalling the record for the fastest five-wicket haul in 19 balls.

Mitchell Starc ended with 3-29 as England's misery was complete.

"It is pretty insane. Just an awesome few weeks, everything clicked and everything worked out," said Australian skipper Pat Cummins. 

"Thrilled for Scott Boland. We have been relentless."

https://www.youtube.com/watch?v=UgLv_4Ap4S8

Ben Stokes resumed on two but his poor tour continued when he has clean-bowled by Starc for 11. Jonny Bairstow made five and when Root was out it was all over, with the tailenders quickly following.

"It is what it is. We have come to dealing with this sort of an environment for a while now," said a dejected Root. 

"Credit to Australia, they blew us away. We have a lot of hard work to do now and come back hard in the next two matches."

- Covid threat -

Whether there would be play at all was in doubt after four members of the England party -- two support staff and two family members - tested positive for coronavirus on Monday.

But all players from both teams underwent PCR tests after stumps and returned negative results Tuesday morning with the first ball bowled on schedule.

England headed to Melbourne knowing they must win to keep the five-Test series alive after heavy defeats in Brisbane and Adelaide, with Australia only needing a draw to retain the urn as holders.

And they fleetingly hauled themselves into contention on the back of a vintage bowling effort from veteran seamer James Anderson, which restricted Australia to 267 in their first innings in reply to the tourists' 185.

But it was only an 82-run lead and any dreams England had of staying in the Test, or even winning it, fell apart in the face of an intense fast bowling blitz on Monday from Starc, Cummins and Boland.

In an hour of mayhem, they removed hapless openers Zak Crawley (five) and Haseeb Hameed (seven), Dawid Malan for a golden duck and nightwatchman Jack Leach (0), leaving England staring into the abyss on 31 for four after another stunning collapse.

- 'Clueless' -

Once again, their hopes rested with Root, who resumed on 12, and star all-rounder Stokes, still 51 runs behind.

Stokes has failed to fire this series but flogged Starc for four to show intent, only for the New South Welshman to respond in devastating fashion two balls later with a fuller, tighter delivery that clattered into the stumps.

Root took a nasty blow in the groin area off Cummins on 23 and eventually went for 28, caught by David Warner at slip off Boland.

Despite the dismissal it capped an incredible 12 months for Root with the bat, ending the calendar year with the third most Test runs (1,708) in history, surpassed only by Pakistan's Mohammad Yousuf (1,788 in 2006) and Viv Richards (1,710 in 1976).

England's miserable batting late Monday, which followed collapses in Brisbane and Adelaide, was castigated by the British media.

"Gutless England batsmen deliver full spectrum of ineptitude," screamed The Daily Telegraph while The Sun slammed "Clueless England".

Cummins warns even more to come

Skipper Pat Cummins said the way his team ripped England apart to retain the Ashes on Tuesday showed the strength of Australian cricket -- and warned they were only just getting started.

The Australian attack destroyed tourists England for 68 in their second innings of the third Test, with Scott Boland taking an incredible 6-7 off four overs on his debut.

It equalled the record for the fastest five-wicket haul, in 19 balls, and came after Jhye Richardson -- a late replacement for injured regular Josh Hazlewood -- took five wickets in the second Test at Adelaide.

"A great sign of the strength of Australian cricket. We were really confident Scotty would do a great job. Maybe not six for seven!" said Cummins.

"Outside of the actual results, there have been so many other positives -- a couple of debutants, a strong squad.

"These three victories really feel like we're setting ourselves up for the next few years and on."

Along with Boland, wicketkeeper Alex Carey also made his debut this series, in for Tim Paine, who stood down as captain and player in the weeks before the Ashes over a lewd text-message scandal.

Seamer Michael Neser also played his first match, in Adelaide, performing admirably when Cummins was ruled out at the last minute as a close contact of a Covid case.

Cummins said Australia's recent victory at the Twenty20 World Cup had given them the belief "that we are right up there with the best teams in the world".

"We went into the series really confident. Losing Painey obviously wasn't ideal, but as soon as we knew that was going to be the case, we knew we had our jobs to do and a lot of really confident players around that," said Cummins.

"I just feel like it's building, we have a great squad of 15 or 20 guys we're working from and I think we have got options for anywhere in the world."

Sydney Ashes Test not at risk

The "sacred" Ashes Test in Sydney will take place as scheduled next week even as Covid threatens to disrupt the series, the New South Wales health minister said on Tuesday.

Two members of England's support staff and two of their family members tested positive for coronavirus at the Melbourne Test on Monday and were placed in isolation.

The England team and management underwent rapid antigen tests but were allowed to head to the ground when they returned negative results, despite being close contacts. Subsequent PCR tests for the Australia and England teams were also negative.

But the rules are different in New South Wales state, where Sydney is located and which is experiencing a surge in infections.

In NSW, anyone considered a close contact must isolate for seven days.

That would mean the Test would have been abandoned if it had been in Sydney, which hosts the fourth Ashes Test from January 5.

NSW health minister Brad Hazzard attempted to dispel fears that the match could be disrupted by the state's contact-tracing rules.

"The SCG (Sydney Cricket Ground) Test is sacred, an important date at the start of the third year of our life with Covid-19," he said in a statement.

"I want to assure the cricket-loving public, under our rules any players with exposure to a known case of Covid-19 would be asked to test and isolate only until a negative result was received.

"If there are any cases within the teams, their support staff, or families, we will work with the people involved to ensure they are safe, and there is as little disruption to others as possible."

The fifth and final Test is in Hobart, where there have been far fewer Covid cases than Sydney.

Root makes history

England lost the Ashes in humiliating style on Tuesday but for Joe Root it has been an incredible 2021 with the bat, the skipper ending the calendar year with the third-most Test runs in history.

His dismissal on day three of the third Test in Melbourne for 28 left him with 1,708 runs for the year, at an average of 61.00, behind only Pakistan's Mohammad Yousuf (1,788 in 2006) and West Indian legend Viv Richards (1,710 in 1976).

More questions will be asked of his captaincy after England were well beaten again by Australia, but Root has been in brilliant form with the bat this year.

He moved past the likes of Sunil Gavaskar and Sachin Tendulkar to chalk up 1,600 runs at the second Test in Adelaide, and then edged South Africa's Graeme Smith (1,656 in 2008) in Melbourne.

Root, however, had far more innings to compile his total -- 29 to the 19 of both Yousuf and Richards.

"I obviously feel like I'm playing really nicely at the minute but I would obviously swap it all for Test match wins," he said after England's innings and 14 runs thrashing in Melbourne.

"Any player will tell you that there's no better feeling in cricket than winning a Test match."

"It's great that I feel like my game is improving and evolving still as a player, even having played quite a lot of cricket, and I'm desperate to keep doing that," he added.

But the Yorkshireman, 30, is still searching for a first Ashes hundred in Australia. He has two more Tests to do it.

"I think I probably wanted it too much, I was too desperate and it had probably a negative impact on the way I played, I put too much pressure on myself," he said ahead of the tour of his will to succeed in Australia.

The extent to which England have relied on Root this year is demonstrated by the numbers.

Second in the pecking order is maligned opener Rory Burns, who scored 530 this year at 27.89, then Jonny Bairstow with 391 at 24.43.

Test scoreboard

Scoreboard at the end of England's second innings on day three of the third Ashes Test between Australia and England at the Melbourne Cricket Ground on Tuesday:

England first innings 185 (J. Root 50, J. Bairstow 35; P. Cummins 3-36, N. Lyon 3-36)

Australia first innings 267 (M. Harris 76, D. Warner 38; J. Anderson 4-33)

England second innings (overnight 31-4)

H. Hameed c Carey b Boland            7

Z. Crawley c Carey b Starc            5

D. Malan lbw Starc                    0

J. Root c Warner b Boland            28

J. Leach b Boland                     0

B. Stokes b Starc                    11

J. Bairstow lbw Boland                5

J. Buttler not out                    5 

M. Wood c & b Boland                  0

O. Robinson c Labuschagne b Boland    0

J. Anderson b Green                   2    

Extras (lb5)                          5

Total (all out; 27.4 overs)          68 

Fall of wickets: 1-7 (Crawley), 2-7 (Malan), 3-22 (Hameed), 4-22 (Leach), 5-46 (Stokes), 6-60 (Bairstow), 7-61 (Root), 8-65 (Wood), 9-65 (Robinson), 10-68 (Anderson)

Bowling: Starc 10-3-29-3, Cummins 10-4-19-0, Boland 4-1-7-6, Green 3.4-0-8-1 

Toss: Australia

Result: Australian won by an innings and 14 runs

Umpires: Paul Wilson (AUS), Paul Reiffel (AUS)

TV umpire: Rod Tucker (AUS)

Match referee: David Boon (AUS)