Is Lehman's son ready to fill vacant No 6 spot?

Son of 'Boof' has Maxwell looking over his shoulder

Ashes auditions for Australia's vacant number six spot have seen a number of leading candidates fluff their lines in the domestic Sheffield Shield but Jake Lehmann's strong form could force an awkward decision at the selectors table where his father sits.

Lehmann, the son of Australia coach Darren, has been closely watched since emerging with a trio of first class centuries in the 2015/16 season, and has built a respectable first class average of 44.95 from 29 matches with South Australia (SA).

He struck his sixth first-class century with a first-innings 103 against Victoria and backed that up with a 93 to be awarded Player of the Match as SA fell two wickets short of an outright victory on Tuesday.

Another big score in the third round could force his father 'Boof' out of the room when selectors discuss the squad for the first Ashes test in Brisbane starting Nov. 23.

Even as the 25-year-old pressed his claims, Victoria batsman Glenn Maxwell, probably the strongest candidate for the middle order position, was fighting his own battle to win favour, scoring 64 after managing 60 in the first innings.

Dismissed cheaply twice in the opening defeat to Queensland, all-rounder Maxwell's twin half-centuries may go some way to easing doubts about his consistency.

Maxwell struck a fine century when batting number six in Ranchi against India in March but has failed to reach 50 in seven Test innings since.

Few others, barring 23-Test Shaun Marsh, who hit a 91 for Western Australia (WA) against a test-quality New South Wales (NSW) attack, have raised their hand for an Ashes spot.

Marsh's state team mate and younger brother Mitchell has managed only 46 runs so far in the Shield, the fast-bowling all-rounder failing twice against NSW.

Another WA all-rounder Hilton Cartwright, who played at six in Australia's last Test against Bangladesh, crashed out with a pair of ducks and would appear out of the running.

Questions over the wicketkeeper position also remain, with Matthew Wade failing to shore up his spot with a decent score for Tasmania and his NSW rival Peter Nevill doing little with the bat to dislodge him.

Australia's attack, by contrast, is settled and has been humming along nicely, with pace spearhead Mitchell Starc firing an ominous Ashes warning with a pair of hat-tricks for NSW in the same match against WA.

Starc's performance moved fellow left-armer Mitchell Johnson, the man who terrorised England's batsmen during the 5-0 whitewash in the 2013/14 series, to tweet his approval.

"Seriously 2 hat tricks in the same game ... Now time to rip in to the poms," wrote Johnson.

Starc's NSW team mate and test captain Steve Smith was also impressed, but spread the praise around to fast bowlers Josh Hazlewood and Pat Cummins.

"I thought he bowled like an absolute genius, he's a superstar," Smith said of Hazlewood's six-wicket haul.

"Patty Cummins has had a couple of good games as well so they're up and going and bowling really well. So that is positive signs for us."