In remarkable scenes at Hurstville Oval, the visitors - who were cruising at 0-179 in their second innings - lost all 10 wickets for 44 runs. The final three were claimed in successive balls by the Australian left-armer just as he had done on Monday.

Starc and Steve Smith's Blues side celebrated wildly as an edge from Warriors batsman Jonathan Wells flew to the captain in the slips to complete the stunning finale and a 171-run victory, their second of the season.

It was the first time a player had ever claimed two hat-tricks in a single first-class match in Australia and only the third time an Australian had achieved the feat ever. The previous ones were Jimmy Matthews in a Test against South Africa at Old Trafford in 1912 and Albert Trott in a county match for Middlesex in 1907.

A reverse-swinging Starc looms as a nightmare for England's tail-enders this summer.

"They've found it pretty hard for a long period of time, the shape that he gets, the angle that he creates when going so wide," Smith said.

"It's difficult for batters, let alone tail-enders. To take two hat-tricks in a game ... most people are lucky to take one in their career. They're not easy to come by."

Starc capped a standout display from the Blues' all-Australian fast bowling attack as they gear up for the first Test at the Gabba. Starc and Pat Cummins will now sit out the final pre-Ashes Shield round in Queensland next week while Josh Hazlewood will have one more tune-up game there.

"I thought (Hazlewood) bowled like an absolute genius, he's a superstar," Smith said. "Starcy, I think, has probably taken a little more time to get going and get some rhythm. But the back end of today showed why he's world-class. Patty Cummins has had a couple of good games as well. They're up and going and bowling really well."

Incredible scenes!??? NSW Blues (@CricketNSWBlues) November 7, 2017

The performance of the Australian quicks came as uncertainty continued about the make-up of Smith's XI in Brisbane, with the search for a No.6 batsman taking another twist after frontrunner Hilton Cartwright had a pair.

The good news is that Smith is back in good touch after posting 127 on day four, his first hundred since India in March, but if selectors had hoped to have a batting order pencilled in around him by now those plans hit a hurdle.

Cartwright, 25, was widely considered the favourite to land the vacant middle-order position against England, with the extra overs he can offer with the ball a bonus, but he blew a key audition after his second duck of the match.

While Peter Nevill appears likely to win a recall as Australia's wicketkeeper a year after he was dropped, the first two rounds of the Shield have revealed no standout candidate to bat at No.6.

Cartwright's state teammate Cameron Bancroft, however, has done his cause no harm. Against the best four bowlers in the country the West Australia opener followed up an unbeaten 76 in the first innings with 86 on the final day.

This interstate round, however, has thrown up more questions than answers. Trevor Hohns' panel now find themselves still contemplating a middle-order field that includes Cartwright, Bancroft, Jake Lehmann, Shaun Marsh and Glenn Maxwell.

Marsh has enjoyed a fine start to the summer and was untroubled and on the cusp of a century on Tuesday when, on 91, he flashed at a wide ball from Hazlewood in the final over before tea. His angry reaction at his dismissal suggested he knew a big score had gone begging.