Joe Root has always been a key component in England's Test line-up but, such is the current fragility of their top order, it is probably no exaggeration to suggest that their Ashes hopes will stand or fall on their captain's batting form.
Since the departure of the ever-dependable Alastair Cook, England have tried umpteen top-three combinations without ever finding anything of substance, a situation that has piled even more pressure and responsibility on Root.
After a dip from 2018-20, he has risen to that challenge this year, chalking up 1,455 runs at an average of 66.1 to reclaim his position at the top of the world rankings. England have scored seven centuries in 2021 - Root making six of them.
Even more impressive is that as well as operating amid the fallout of an inconsistent top three, he has also been largely without the middle-order bulwark of Ben Stokes behind him.
Already carrying the extra strain of captaincy, it must be draining for Root knowing he probably needs to be padded up and ready almost from the off in every innings, rather than joining the fray with the contest well under way and the shine taken off the new ball and the opposition's main strike bowlers.
Despite those repeated top three fails, he has resisted calls to move up the order. Root averages 53.4 batting at four and a remarkable 67.8 at five but that dips to 38.7 at three and 41.7 from his 11 innings as an opener.
In his personal case, it's very much a case of "if it ain't broke, don't fix it." Root's tally of 9,278 runs from 200 Test innings leaves him second behind Cook (12,472) in England's all-time list while he is level with Kevin Pietersen in second place on the centuries list with 23 - 10 behind Cook.
In Australia, however, Root still has something to prove. He has yet to score a century there and in his two previous away Ashes series averages 38 from nine Tests.
Trying to explain that relative dip, Root said recently: "It's the one place where I feel like I have underperformed and not got the best out of myself, so it's a great driver for me to go and do it this time round.
"I think I probably wanted it too much. I was too desperate, and it had probably a negative impact on the way I played and I think one of the things that has really helped me this year is stripping a little of that back, really going and enjoying my cricket."
While Root's batting has been spectacularly successful this year, his captaincy in the field has attracted a fair amount of criticism and, of course, it will face the ultimate examination over the next few weeks.
With the bat he has played a big part in two home Ashes series wins but as a captain the "big one" remains a glaring hole in his otherwise glittering CV, losing badly on England's last visit then seeing Australia retain the urn via the drawn series two years ago.
"It's something you’re desperate to do in your career," he said this summer after becoming England's most successful captain in terms of Test victories. "I think as England captain you are always judged slightly on how you do in Ashes cricket."