The greatest sportspeople have an impeccable instinct for when to stop.
rom Michael Jordan giving the Chicago Bulls their sixth title with his second-last-ever throw, to Pete Sampras winning the US Open as a supposedly washed-up 30-year-old, a last, brilliant flourish tends to burnish the legend and give fans closure.
Rory Best hopes that Japan will be all that for him, and us.
When Best woke up the morning after his emotional farewell at Lansdowne Road earlier this month, the very first thing he thought of when he opened his eyes was the challenge of the Far East.
Captaining the greatest Irish team of this, and maybe any, generation, is every bit the honour Best described in his emotional speech on the pitch, but there is also a burden of expectation which comes with the finality of the swan song.
"I know it's going to be the last time, and that's difficult, because in my head I can see all the possibilities. I know what it looks like when it goes badly as well as when it goes well," he says.
"When you're younger, you have this kind of ignorant courage where you're sort of oblivious to what might go wrong. I know what can go wrong. But I will focus on trying to enjoy it. Since I've turned 30, I've played my best rugby, and part of that has actually been it not being the be all and end all in life.
"Before, I was always looking so far ahead at different tournaments coming up that I could never enjoy fully what was in front of me. But this is the last time, and as badly as I want us to do well, I want to take it all in, too."
The warm send-off Best received at the Aviva after this month's win over Wales was a fitting testament to his legendary career.
Best led Ireland to a Grand Slam last year, and he was also there for the clean sweep of the 2009 Six Nations. He has been on sides that beat the All Blacks twice, and captained the national team to heights it never reached before.
But there have been notable lows, too. The most recent came in August, when he captained the national side to a painful defeat against England at Twickenham.
To Best, that game seemed to represent "how fragile our success really is, that if we're not on form, and if we don't prepare, that we can easily return to days like that, which we would never want to return to."
The pain of defeat is always a bit more memorable, and a bit more motivating, than the succour of victory, Best explains.
"The fear factor, for me, is the big driver. I do fear failure. That's useful though. A little bit of paranoia and uncertainty is a great engine," he says.
"It makes you want to be the best. I have seen that in a lot of top players over the years. They're often not as confident as they come across. Paul (O'Connell) called it a battle.
"And he is someone you would have never thought was struggling with any kind of confidence, but part of the name of the game is telling the right lies with your body language and Paul was able to do that."
In his twenties - he is 37 now - Best struggled with confidence and self-discipline. He recalls a moment during an early tour with Ireland when he was mortified in front of a whole stadium.
"I remember being told I was coming on with about 20 minutes to go," he explains, "and I was stretching and getting ready, and then they said to me, 'Oh no we had the wrong guy (they wanted Neil Best).' I said to myself, 'How bad am I that they could see me warming up and still didn't want to put me on?' Even on a human level it was just a bit pitiful. I knew I needed to sort myself out."
Best knew that alcohol was at the core of his personal and professional problems.
"I said to myself, 'I need to sort myself out.' I decided to go off the drink and that changed my life. Mondays weren't about getting through the day to get home and go to sleep, they were actually about training and improving."
He could sense that all was not well on the home front, too. "I wanted to do it for my family life as well. My wife, Jodie, and I, we were going out at the time, and I would have seen her after the game on Friday, and then not again until Sunday, because I'd been out with the team the whole time.
"And then when I'd be with her again on Sunday, I'd be falling asleep the whole time. We weren't in a great place and she was getting kind of annoyed and I could understand why. After I stopped drinking, I could be there in mind and body the whole weekend, and our relationship went a lot better."
Best has been with Jodie for most of his life. They were childhood sweethearts who met in geography class when they were 15.
The couple got married in Richhill, Co Armagh, in the summer of 2009, and are now the proud parents of Ben, Penny and Richie. Ben is already an aspiring rugby player and while Rory encourages him, he's also wary of the pressure that comes with the family name.
"I'd hope, whatever he does in the game, that he's just able to enjoy it and not feel under extra pressure because of the name or that he's my son," he says.
Growing up, Best knew all about that kind of pressure. His brother, Simon, was five years older and an outstanding player who won a place on the national side as a teenager.
"My brother set a high bar," Best recalls. "He was captain of Ireland Schools and captain of Ireland and Ulster under-21s. That was such a big deal at home. I wouldn't say that I ever really felt in his shadow, but it was a good bit of pressure to live up to what he'd done.
"It was nice going to trials and people know your name, but at the same time, I'm very competitive and he set this bar high and I was determined to get over it, too."
Best lived his teenage years through some of the bad old days in the North. In 1998, a murder put the little village where he grew up - Poyntzpass, Co Armagh - into international headlines.
Two childhood friends, Philip Allen, a Protestant, and Damien Trainor, a Catholic, were murdered by Loyalist gunmen.
On the evening of the killing, the men had been discussing Allen's forthcoming wedding, at which Trainor was to have been best man.
It became one of the most notorious incidents in the history of the Troubles, which Best says cast a pall over his otherwise sheltered childhood.
"As a kid you would see it constantly on the news. I can remember being afraid to go upstairs after seeing the news one night, but it might have been that I didn't want to go to bed as much as anything else," he said.
"I went to school in Portadown - a good school but a rough area - but it was already the very late 1990s then, and the Good Friday Agreement was about to happen. The things that players in the 1980s experienced never really impacted me; I was lucky in that respect."
And yet, the symbolism of the North would rear its head, even on the pitch. The national team is, of course, made up from players from all over the island, and it has often been commented upon that Best, a Protestant, refuses to sing either Amhran na BhFiann or its fairly horrendous, rugby-specific substitute, Ireland's Call.
Some observers read a snub into his refusal, but he explains it in terms of his will to win. Riling himself up before a game by bellowing out a song would not be conducive to maintaining the cool, calm head that a captain needs.
He points out that his family have been going to Donegal, where his father bought a holiday home, since 1982. And he adds that the broadening of Ulster rugby to include southern counties is an initiative he welcomes.
"The big push to include Donegal, Cavan and Monaghan is a great move I think; we're not Northern Ireland, we're Ulster," he says.
Throughout his long career Best always seemed like a touching throwback to an amateur era - he still works on his family farm - and a rugged riposte to the Instagram pretty boys who began to populate the upper echelons of the sport.
"I would like to be an Instagram pretty boy," he ventures meekly when I raise the subject. "But I don't think that's what God had in mind."
Nonetheless, he is popular with sponsors, and on the day we speak he is promoting the Specsavers 'Don't Suffer in Silence' campaign and helping to fight the stigma still associated with hearing loss and hearing aids. He has been proactive with encouraging his parents to get their hearing checked.
As captain of Ulster, Best spent much of his career duelling with Munster's Jerry Flannery for the right to start in the Ireland jersey. He says that, unlike the rivalry between Ronan O'Gara and Johnny Sexton, things never got personally heated between the two men.
"The difference with Ronan O'Gara and Johnny Sexton, was that it corresponded with Leinster and Munster duelling to be best in Europe, whereas Ulster were considered a bit of an also-ran. With me and Jerry, it was me coming off and him coming on, and, to be honest, I felt he taught me a lot about how to be a good pro."
The culture of Ulster rugby has been much debated in the wake of the Belfast rape trial, at which former Ulster players Paddy Jackson and Stuart Olding were acquitted of raping a 19-year-old student. Best was widely criticised for attending the trial just days before Ireland's Six Nations match against France.
There were widespread calls for Best to give up the Irish captaincy, while the hashtag #NotMyCaptain trended on Twitter.
Following Ireland's victory over France, Best later revealed he attended the trial "because I am on record as a character witness. It was important I got both sides of the story."
Judge Patricia Smyth added that Best was "instructed to attend by senior counsel". Reflecting on it all now, Best says, "I had no idea that it would become such a circus, I would never have put myself or my family in that position if I had known."
Jackson went on to sign for London Irish, prompting one of the club's mains sponsors, Diageo, to sever ties with the club. At time of writing, the club's coach, Declan Kidney, had decided to leave Jackson out of the team for a friendly game in Cork, at which protests were planned.
Does Best feel that protests against Jackson are justified, or does he believe that the player should be allowed to continue his career in peace?
"People are entitled to their own opinion and they have a right to protest, there's nothing I can say to change that," Best says, "but at the same time I also think Paddy is certainly entitled to get on with his life and his career. The truth of it all is probably somewhere in the middle."
Retirement can be a tough proposition for sportsmen. The sudden lack of purpose can wreak havoc with athletes used to a daily grind of training and competing. Best says this is the right time for him, however.
When the final whistle blows in Japan, he will know he did all he could.
"I've no resentments of the terms on which I'm leaving the game," he says. "I'm not being forced out by injuries or something else. Mentally, I'm so happy that I can put everything into this World Cup and when it's over I can look back on a career I'm proud of."
Rory Best continues to tackle the stigma associated with hearing loss for Specsavers Audiologists' 'Don't Suffer in Silence' campaign. He is encouraging people to be extra mindful of family and friends who might be struggling with their hearing, in his role as Specsavers Audiologists' ambassador. For further information, see specsavers.ie/hearing
Portrait by Kip Carroll