Ashes 2015: Who's hot and who's not for Australia?

Shane Watson (left), Mitchell Johnson (centre) and Steve Smith have differing Ashes prospects

Australia's tour opener against Kent offered the first opportunity to assess the form of the men preparing to take on England in the Ashes this summer.

Steve Smith and Shaun Marsh have made their mark with centuries in Australia's first innings, while Mitchell Johnson sent a cold shiver down English batsmen's spines with a menacing three-wicket burst on Friday.

With analysis from Test Match Special commentator Jim Maxwell, BBC Sport weighs up the early talking points of Australia's campaign to retain the urn.

Pace attack - one Mitchell or two?

Josh Hazlewood has 24 wickets from five Tests at an average of 19.08

It may amaze English readers to learn that Johnson's place in the Australia pace attack is the subject of some debate.

The left-arm paceman, who terrorised England's batsmen in the 5-0 series win over England in 2013-14 with 37 victims, was out-bowled by Mitchell Starc and Josh Hazlewood in Australia's recent tour of West Indies.

And with Ryan Harris and Peter Siddle also in the squad, the pace attack for the first Test in Cardiff is by no means set in stone.

As if to prove a point, however, Johnson waited only six balls before taking his first wicket of the tour as he trapped Daniel Bell-Drummond lbw at the end of an over delivered at searing pace.

Two further scalps in Johnson's third spell left Kent batsman Rob Key joking that he doesn't get paid enough to face a bowler of the Australian's calibre and speed.

Maxwell's verdict: "Given how much Johnson got into the heads of England in Australia, I'm sure he'll be playing. If they are at their best, I think Harris and Johnson are still at the top of the pecking order, then Starc and Hazlewood.

"But Hazlewood's recent form suggests he's going to be hard to leave out. So I suppose it depends a bit on how well Harris comes out of this game, whether he's right to get through a fair bit of work and do his best in Cardiff or will they just hold back, as they did last time, and save him for Lord's."

Opening up - Rogers or Marsh?

Shaun Marsh has 859 runs from his 14 Tests

With David Warner far more likely to punch a quick hundred than a fresh-faced England cricketer these days, his place at the top of the Australian batting order is secure.

That leaves two men - Chris Rogers and Shaun Marsh - fighting it out to walk out to bat with him in Cardiff.

Rogers is the strong favourite, given his impressive record in the English county game and the fact he has scored fifties in each of this last six Test innings.

Marsh did not entirely convince as a stand-in when Rogers missed the Windies Tests with concussion, scoring just one fifty in four innings.

However, his flawless hundred against Kent, delivered while Rogers was compiling a much less convincing 84, showed him to be a more than capable alternative.

Maxwell's verdict: "I think there will be debate. Rogers may keep his spot in the short-term but Marsh seems to be favoured by some of the men making decisions and could grab the spot. Marsh has an extraordinary capacity for making Test hundreds, but also an extraordinary capacity for missing out completely - that's why he doesn't have a great average.

"If you go back over the past 12 months, the Rogers-Warner axis is going very well but the time is coming when Marsh will supplant Rogers in the team."

Steve Smith - have England got his number?

Steve Smith is the world's top-ranked Test batsman

Smith's transformation from an ungainly number six to the top of the Test batting rankings is one of modern cricket's most remarkable tales.

He remains a fidgety, somewhat ungainly, presence at the crease but he possesses a sharpness of eye and quickness of hand that were in full evidence during his seemingly effortless hundred against Kent.

Smith scored 13 fours and a ruthless pull for six in his 111 before he took pity on the bowlers and retired himself out.

Smith's record in England, where he averages 34 compared with 66 in Australia, hints at a vulnerability against the moving ball and Graeme Swann has suggested the hosts could get the better of him if conditions play to their strengths this summer.

Maxwell's verdict: "I think every player is vulnerable against the swinging ball. It doesn't matter how good you are, anyone can nick off in the first part of your innings. But I'd be surprised if Smith doesn't score more than 500 runs this series. Plenty of people have struggled in recent times to get him out. He has such extraordinary hand-eye coordination, great technique and so much more confidence that he had a few years ago."

Is Watson still the all-round package?

Mitchell Marsh has averaged 37.42 with the bat from his four Tests

Australia's selectors also have a decision to make over the all-rounder slot with Shane Watson facing competition for this place from Shaun Marsh's younger brother Mitchell.

Watson has two Ashes hundreds on his CV, but has not reached three figures in 16 Test innings, while Marsh has shown promise with bat and ball in the one-day set-up.

At Canterbury, Watson groped around for 21 before he was spectacularly caught by Joe Denly. Marsh looked the more fluent, cracking six boundaries in a 26-ball 30.

Maxwell's verdict: "I think we're moving towards the point where Marsh will replace Watson, whose batting was pretty scratchy here as it has often been recently. But Watson is so good at first slip and can still bowl quite handily. I think they'll start with Watson but Marsh is very much in the reckoning somewhere along the line."

Will Australia brush aside the Dad's Army tag?

The sharpest barb of the pre-Ashes war of words has been fired by former Australia pace bowler Jason Gillespie.

He labelled the team a "Dad's Army" in reference to the fact that 10 of their 17-man squad are aged over 30. Chris Rogers and Brad Haddin are both 37, and Ryan Harris and Adam Voges are 35.

In contrast, Ian Bell is one of only two players over 30 in England's likely starting line-up for the first Test.

Could it be one tour too many for some of Australia's golden oldies, or will their greater experience tell against England's young pretenders?

Maxwell's verdict: "There is no retirement age for cricketers in my opinion. I saw Clive Lloyd play at pushing 40 and he was still a great player. I think the age is irrelevant if the players are performing and in Adam Voges's case he had a stunning first-class season and he's followed that up with a century on debut.

"Unless there's an obvious sign that a player is losing that millisecond of judgement, it's not really an argument as long as they are keen and motivated."