When England's selectors decided to drop Graham Thorpe and replace him with Kevin Pietersen at the start of the Ashes series, they only did so after a lot of soul-searching.
Magic moment: Pietersen reaches three figures at The Oval
Thorpe's reputation as a man who could fight England's corner when the going got tough was well established.
But in opting for Pietersen, chief selector David Graveney said: "We firmly believe he has the potential to become a world-class player in England's middle order and a genuine match-winner."
At The Oval, on the final afternoon of an epic five-match series, Pietersen proved the selectors right with an innings of 158 which showed he has the bottle to go with the bravado.
He performed respectably with the bat in the first four Tests, scoring 301 runs at an average of 43.
But the manner of some of his dismissals raised question marks about whether he had the patience to thrive in the five-day game.
Writing in the Daily Telegraph newspaper last Friday, former England opener Geoffrey Boycott said: "Pietersen's hubris seems to be getting the better of him.
"He wants to be the superstar, he wants the acclaim and the adulation, but he has not yet put in the performances to back up that attitude."
But Pietersen enjoys star billing - the role of supporting player is not for him.
And by scoring a maiden Test century with the Ashes at stake and under the severest pressure a player could endure, the 25-year-old proved he can back up his confident words with deeds.
Pietersen had to fight to survive against Brett Lee at his fastest
Australia only had themselves to blame as two slip chances went begging, the easiest put down by Shane Warne, Pietersen's county captain at Hampshire.
It was a slip catch Warne would expect to take 99 times out of 100.
He, more than any other Australian player, knew how costly that could be, having seen him up close as a Hampshire team-mate at the start of the summer.
Pietersen's path to Test cricket was long, but travelled with a single-minded purpose.
He left his native South Africa because of the racial quota system then in place in domestic cricket and made the life-changing decision to pursue his career in England, the country where his mother was born.
Four prolific summers with Nottinghamshire followed, leading to a call-up to England's one-day squad.
He was undaunted by a return to his homeland where he answered jeering from the crowd with 454 runs at an average of 151, including three hundreds - one of them the fastest by an England player in a limited overs game.
Such was his impact that when the BBC was planning its radio coverage of the Ashes, Pietersen was chosen as the poster boy to put alongside Warne - even though he had yet to win a place in the team.
Pietersen is a colourful character on and off the field
Moving to Hampshire from Trent Bridge at the start of the summer, he soon struck up a firm friendship with Warne - a friendship which became an intense rivalry once the Test series got under way.
Describing Australia, the world's best team, as 'bullies', Pietersen promised: "We're going to stand up and be counted."
He certainly did that at The Oval where two ferocious 95mph bouncers from Brett Lee almost separated his head from his shoulders.
And his determination found vivid expression at the moment of reaching his century as he punched the air with both fists before accepting a standing ovation from the sell-out crowd.
The good news for England is there should be lots more to come.