'Longevity defines him' - how long will Ronaldo go on?

Fifa World Cup qualifier: Republic of Ireland v Portugal

Venue: Aviva Stadium, Dublin Date: Thursday, 13 November Kick-off: 19:45 GMT

Coverage: Live text commentary on BBC Sport website

In July 2009, Cristiano Ronaldo arrived in Dublin as the most talked about footballer in the world.

In the 16 years that have followed, and even as he starts to talk openly of retirement, it is remarkable how little has changed.

Then, the Portuguese superstar was in town to make his Real Madrid debut in the somewhat incongruous surrounds of Shamrock Rovers' Tallaght Stadium.

On Thursday, some eight miles across the city at Aviva Stadium, he will look to ensure another significant milestone by securing qualification for the sixth World Cup of his career in North America next summer, which he has now confirmed will be his last.

That bow in the famous white shirt came months after he was awarded the first of his five Ballons d'Or.

While it has been eight years since he picked up his most recent, the passing of the torch on the pitch from himself and Lionel Messi - who between them won the award 12 times in 13 years - to the likes of Ousmane Dembele, Erling Haaland and Lamine Yamal has not been mirrored off it.

As evidenced by an attention-grabbing interview with Piers Morgan last week, nine months after his 40th birthday there is still no player in the world who generates headlines like the former Manchester United great.

Ronaldo is not alone in continuing at a high level long after what was once considered retirement age.

LeBron James, who came into the NBA as a teenager, has stretched his career in the league to the point that the 40-year-old is playing a second season with his son as a Los Angeles Lakers team-mate.

Only last week, after claiming the 101st title of his career, tennis great Novak Djokovic signalled his intention to defend his Olympic title at Los Angeles 2028, by which stage he will be 41.

In the opinion of Portuguese football journalist and author Miguel L Pereira, perhaps the difference is how central the length of Ronaldo's playing career is becoming to his story.

"I think it defines him, defines his personality," he said.

"I think he was always very concerned how he would be remembered, how people in 15, 20 years will talk about him.

"I think from the mid-2010s, he realised that he wouldn't win the emotional comparison with Messi so he decided to do that based on trophies, based on goals scored, based on things that were countable. I think that's why he keeps on going."

Already the leading goalscorer in men's international football and the Champions League, and one of only six players to play at five World Cups, what could be Ronaldo's next targets?

There is no agreed upon database to establish men's football's all-time top scorer, but Ronaldo is already over 950 career goals and previously told former team-mate Rio Ferdinand, external reaching 1,000 was the "most important" remaining target for his career.

Such has been Ronaldo's longevity, he has played international football with three generations of team-mates.

When making his international debut against Kazakhstan in August 2003, he was captained by Fernando Couto, a player born when England were the holders of the World Cup and before the break-up of The Beatles.

After winning Euro 2016 alongside a key group of those around his own age, for this week's qualifiers against the Republic of Ireland and Hungary, he skippers a squad containing three players not even born at the time of his first cap.

Twenty-two years in the same side has required a reinvention, one where the days of powering in from wide positions is a thing of the past.

Instead he is left as an orthodox number nine, an increasing anomaly in the modern game that presents something of a tactical conundrum for his manager Roberto Martinez and team-mates.

It was telling that when former Manchester United team-mate John O'Shea, now assistant coach for Republic of Ireland, was asked on Monday how to stop Ronaldo at the Aviva Stadium, he spoke of the need to clear crosses and defend the box.

"He doesn't run much, he's more of a forward when strikers that only play in the box are almost extinct right now," said Pereira.

"He's the sort of player that doesn't fit with the patterns that you see especially in top sides today. He wouldn't play at PSG or Bayern Munich, he wouldn't be able to.

"Some of those [younger] players who have grown used to playing for teams like PSG or Chelsea or Barcelona or Real Madrid have been used to another rhythm, another way of connecting with their forwards can feel somehow limited by it because they cannot do the same things that they do at their clubs."

For some, Portugal's Euro 2024 exit on penalties at the hands of France, which came with Goncalo Ramos and the late Diogo Jota left on the bench, felt a natural end-point yet there have been 13 international goals since.

Ramos' case to replace his legendary captain in the national side is not helped by his minutes at Paris St-Germain.

When it comes to whether the current iteration of Ronaldo is a help or hindrance, Pereira concludes "there are two sides to every story" - but there remains no doubt over who is the central character.

With a sixth World Cup on the horizon, quite how long this final chapter will last remains unclear.