There was a sense of shock about the make-up of the 13-man squad when it was confirmed on Friday but also anger and frustration from players at state level, and not simply among those who were dropped from Australia's last Test side or were in the frame and missed out.

Tim Paine's stunning elevation from the Tasmania back-up to the Test wicketkeeper's job and Shaun Marsh's selection at No.6 were the main sources of discontent.

Players are scratching their heads about perceived inconsistencies in selection decisions and in the messaging from the panel over the past 12 months. A range of grievances have been voiced privately to Fairfax Media since the team was revealed.

There are questions how Paine, not the first-choice 'keeper for his state and whose first-class average is under 30, could be chosen on the strength of a half-century for a Cricket Australia XI against England in Adelaide and an unbeaten 71 playing as a batsman only for Tasmania against Victoria.

While there can be little argument with the ascendance of an in-form Cameron Bancroft, there is also bemusement about Marsh's inclusion at the age of 34, which reverses a trend of picking younger players such as Hilton Cartwright, Ashton Agar and Nic Maddinson in the past year and leaves others in the older generation that were overlooked even more uncertain about what selectors want.

Dumped incumbents such as Matthew Wade - who now faces the prospect of playing as a batsman only for Tasmania when Paine comes back to state cricket - and Glenn Maxwell, who featured in Australia's last four Tests and scored a maiden hundred in one of them in India, would also have reason to query the system.

Even if Australia reclaim the Ashes and the selectors look like geniuses, it is increasingly clear they will be left with a domestic playing group that is unsure of where it stands.

Shane Warne on Friday led the reaction to the first Test selection by describing Australia as "confused" but Lehmann on Sunday strongly defended the panel's choices.

'Let's get positive': Darren Lehmann in the nets at the Allan Border Field during an Australian training session before the opening Ashes Test. Photo: AAP

In the winter Lehmann wrote a letter to past and present players urging them to get behind Australia and he reiterated that message, with Smith's team to begin preparations for the first Test at the Gabba on Monday.

"It was tough but we were very clear the way we wanted to go," Lehmann said. "At the end of the day everyone is entitled to their opinions and we made sure the three Shield games were really important. Everyone got a good hit-out and put their case forward before we selected the side.

"I'd just like all our players, ex-players to be really positive about the Australian cricket team. That would be the way to go. I'm looking forward to everyone getting behind Australia and the contest that's about to unfold."

The national coach explained the decision to pick 32-year-old Paine over Wade and NSW's Peter Nevill was not one made without lengthy consideration. Selectors now regard Paine as a superior gloveman to Nevill, who stands behind the stumps to the Australian Test attack at state level.

"We watched him 'keep a bit with the T20s and the [CA XI] game. He's a high-quality keeper," Lehmann said of Paine.

"It was really all the keepers going at it...whoever performed the best with the gloves and then obviously get some runs.

"I was very impressed with him down in the Adelaide game, I went down for that. He's been very good for us in the T20s and we decided to go down that path."

Asked about Marsh, back in the XI after losing his CA contract and not being taken to Bangladesh in August, the coach said: "We're really confident with where he is at as a player. He's in good form so he'll do well. He's played some important knocks for us. He's really confident in himself."

Lehmann expects that Smith will contribute some overs to the Australian attack with his leg-spin in the absence of an all-rounder.

"He'll have to bowl at some stage I'm sure. England are a quality side and he's got some key wickets against them before," he said.