Johnson is the most experienced player in the Test side by a considerable margin and there are few in the dressing room better placed to share his views on the rigours of international cricket.

he retirements of Michael Clarke, Brad Haddin, Shane Watson, Ryan Harris and Chris Rogers in quick succession have dramatically altered the age demographic in the team.

Smith and coach Darren Lehmann are not in the leadership group, placing more emphasis on senior players to step up and show the way rather than relying solely on the captain.

Vice-captain David Warner, Johnson and Nathan Lyon began the summer as the only three players with certainty over their positions in the team while West Australian stalwart Adam Voges's leadership was recognised when he was installed vice-captain in Warner's absence for the cancelled tour of Bangladesh.

The leadership group in the Australian cricket team is informal, unlike with AFL clubs, and meetings are not structured. Its role is not to discipline and hand out punishments and can be as trivial as organising a team dinner or steering teammates through a tough day on the field.

Quietly spoken and mild-mannered off the field, Johnson has made considerable effort to shoulder more of the leadership burden in recent years.

Last summer, for example, in Adelaide he deputised for Clarke, who had been the public face for the team in the immediate aftermath of Phillip Hughes's death, at the traditional match eve captain's press conference leading into the first Test. More recently he has revealed how the excitement of seeing the next generation of Australian cricket perform in the one-day series after the Ashes was a major factor in shelving retirement plans.

Those who saw him melt in the heat of the 2009 Ashes will be stunned now to learn how much more comfortable he is in the public spotlight. He is now contracted to make appearances on pay TV and is also a media columnist.

Lehmann has already noticed Johnson's greater influence on the side since arriving into camp last week for the Trans Tasman series.

"He's opening up a bit now, we've got him in the leadership group so he has to speak a bit more now which is always pleasing," Lehmann said.

"But he looks keen as mustard, and he really wants to do well. Whatever he decides, he decides, but from our point of view he wants to play cricket for Australia, so we want him to play well and get wickets."

There is also a view that Johnson will thrive on the responsibility of leadership, albeit in an unofficial capacity, at the twilight of his career.

The veteran quick could also play a key role in helping Mitchell Starc find the right balance between having a strong on-field presence and overstepping the mark and earning the wrath of the match referee.