England v Australia, 4th Investec Test, Trent Bridge August 5, 2015

Enormous stakes for Australia

Careers and legacies are on the line at Trent Bridge. If Australia win, Michael Clarke will have one more chance to be an Ashes winner in England. If they lose, big decisions await

As Australia's cricketers, selectors and support staff have prepared for the Trent Bridge Test this week, their movements have been watched by the team performance manager Pat Howard. Though not present at every match Australia plays, Howard has a tendency to turn up at moments of importance, to help the squad where he can but also to gauge how they are progressing and decide on longer term action.

Howard, it should not be forgotten, has considerable powers of oversight, being the man who sacked Mickey Arthur and appointed Darren Lehmann in his stead at the outset of the last Ashes tour. He also accepted the resignation of Michael Clarke as a selector, and rebuffed Shane Watson when the allrounder told him he was reconsidering his own resignation from the vice-captaincy.

Those decisions were all made back in 2013, a year of considerable turmoil for Australia until it ended in the regaining of the Ashes urn at the WACA in Perth. Without that victory, Howard has freely acknowledged he would have been out of a job. Since then he has had less high-profile tasks, and this series his opposite number Andrew Strauss has been the man in the headlines.

Now Howard and the team both know they have reached a critical juncture, one that places them all in the spotlight. The success of the Clarke/Lehmann leadership axis and the Rod Marsh/Lehmann selection ascendancy will be judged heavily on what takes place over the next five days, and beyond that the next two weeks. Should things go well, there will likely be a continuation of the current regime, at least up to the point when Clarke decides to retire.

Defeat, however, would open up a range of possibilities. The loss of this series, following on from that which took place in the UAE against Pakistan last year, would provide legitimate cause for Howard to question whether or not Australia have adopted the right approach to succeed in unfamiliar climes away from home.

Their record on Antipodean shores in that time has been extraordinary, taking in major series wins over England and India plus the return of the World Cup into Australian hands for the first time since 2007. But the free-spirited, aggressive and instinctive play advocated by Clarke and Lehmann has come unstuck everywhere overseas but South Africa, widely acknowledged as the most familiar conditions an Australian team can face overseas.

Beyond this series, Australia's Test team faces tours of Bangladesh, New Zealand and Sri Lanka either side of the home summer. Howard will need to decide whether or not more change is necessary to the backroom staff in order to extract the best from a team that has enormous strength in fast bowling, a sturdy spin bowler in Nathan Lyon and two major batting talents in David Warner and Steven Smith, but little else besides.

While there is obvious pressure on Clarke given his recent run of outs and less nimble than usual captaincy, it is also evident that Lehmann is feeling the strain of the job. He has never coached a single side for this long before, and his visage has changed visibly as this tour has lurched from defeat in Cardiff, to victory at Lord's and then humiliation at Edgbaston. The Brad Haddin episode has also been telling, as the first time Lehmann has found himself leaving some players to question exactly where he stands.

To have his players on tenterhooks was the last thing Lehmann was trying to achieve in keeping an unchanged team from Lord's to Edgbaston, and the strain of the affair has been obvious in both his public pronouncements but also his manner around the squad. This is not the same Lehmann who blew in like the freshest - albeit tobacco-tinged - breath of air in 2013. He is wearier and warier now, trying to challenge his men while wondering how long he might carry on for. More than once he has stated that, like numerous players on the trip, this will be his final Ashes tour.

One example of how the passage of time has affected Lehmann's methods is the light-hearted matter of the "joke of the day" he instituted two years ago. Initially this was the job of each member of the squad to come up with a tale to bring laughter to the team room. Next a selection of celebrities were tried. More recently the support staff had been required to do it. Now on this trip the job has been left to the team's long-time England bus driver "Popeye". A fundamentally sound and useful concept grows increasingly difficult to keep fresh over time.

Trent Bridge is a portentous venue for the Australians to return to. It was here that Lehmann had his first match in charge, and where a magical win was very nearly conjured through the shooting star of Ashton Agar and the grit of Haddin. Back then, Clarke was still speaking daily to Mickey Arthur and Lehmann was finding out about his men. This week will provide perhaps the truest measure of how much they have really learned from his guidance.

Recently Lehmann told Nasser Hussain: "The advantage I had is we weren't playing how we like to play and I could come in with a fresh approach. To the captain and players' credit they bought into it and it runs itself now." Howard will be making assessments about how it is running, as he also discusses the weighty matter of retirements with numerous players. Chris Rogers, Haddin, Clarke and Watson (in Tests at least) will all be pondering their futures, with Ryan Harris already gone from the game. Mitchell Johnson, too, has the longer term to consider.

All want to finish this tour on the best note possible, as Ashes winners away from home for the first time since 2001. But there is an undeniable sense that all know they are being watched to see if they can get things right under this kind of pressure. It is why the team composition for Trent Bridge has been left later than usual, with players unaware of who would be chosen at the time of the team's final training session. Clarke summed up the balance between high stakes and clear heads that needed to be achieved.

"There's no doubt this is my last opportunity to win an Ashes series in England, for me personally and for a number of the guys," he said. "But it comes back to all you can do is give your best. Every single one of the players in this changing room would love to win this Test match, would love to go on and win at The Oval and win the Ashes in England.

"Like we did at the World Cup in West Indies in 2007, the Ashes in Australia recently, the World Cup recently at home. You always want to win, and the only way to do that is by giving your all. It's not going to be from lack of desire, preparation or hard work, if you get beaten you get beaten, but I can guarantee we'll have a red hot crack."

As Clarke and his men give it their best, Howard will be watching, and pondering whether the 2015 Australians, their coaches and selectors will endure as winners. Otherwise they and many of their methods may well be consigned to the Cricket Australia dustbin, as part of another failed attempt to win the Ashes in England.

Daniel Brettig is an assistant editor at ESPNcricinfo. @danbrettig