This is a moment to pause, a stretch of calm before battle, and Paul O'Connell is serene. He is about to enter a nine-month period that could seal a majestic career and, looking ahead to a defining series of matches in the Six Nations, Ireland's captain is in a relaxed mood.

There is a striking difference between the imposing giant in green, dominating the lineout and carrying a mighty force in every run and tackle, and the softly spoken, twinkling O’Connell in conversation. He is one of the greats of European rugby but O’Connell has a light touch off the field.

The 35-year-old, who has played 96 times for Ireland and in seven Tests for the Lions, also knows too much about rugby to make any grand predictions. And so it is striking that O'Connell allows himself to break away from his squad's mantra of concentrating only on their first game as defending Six Nations champions, against Italy in Rome on Saturday, to anticipate an even more important tournament – and a beguiling dream.

“Yeah,” O’Connell says with an emphatic nod, “if you can lift the World Cup you will go down in history. Look at the English team that won it in 2003 – the only northern hemisphere nation to have ever done that. Those guys are legends. It would be great to fulfil our potential and play to the best of our ability in this year’s World Cup.”

O’Connell takes a moment to consider his answer when asked if he also believes Ireland are potential winners of the tournament. “For Ireland to win a World Cup you need a load of things to go your way,” he says. “You need luck with injuries because we don’t have the playing numbers of other countries. But Ireland certainly have a chance of winning the World Cup. You don’t go out and play unless you believe that.

“It’s an outside chance because you look at New Zealand and the way they can pull games out of the fire – or the way they can put teams away very quickly. If you give them any opportunity they’ll take it. You look at South Africa and their size and strength – and then you look at Australia and the way they played against us for those 25 minutes before half-time [when recovering from a 17-0 deficit to draw level before Ireland eventually won 26-23. They’re incredible sides. But, when we get a few things right, and we have some luck, we can live with those teams.

“The way we’ve performed in the last 18 months makes me think that, at our best, we’d certainly have a chance against them. That sharpens our preparation because we know how good we have to be against them. We have to really perform to the best of our ability whereas other countries probably have the luxury of not always being at their best and still winning.”

O’Connell describes World Cups and Lions tours as “forever moments” – in the sense that they are the most significant matches for a player from the northern hemisphere. He has captained the Lions, and also been part of a winning series, but the World Cup is a more hurtful arena for him, between the quarter-final defeats to Wales in 2011 and France in 2003 and the nightmare of 2007.

“It may sound negative but I don’t think we’ve ever played to our potential at the World Cup. Even in 2011, when we played some great rugby and beat Australia, it ended painfully. The Wales game was really disappointing. They were excellent but we played into their hands. It was the same in 2003 . We never played to the best of our ability.

“It has been more disappointing than fulfilling – and 2007 would probably be, God, a period in my career I’ll never forget or really be able to explain. We’re a lot more consistent now – and I don’t think we’ll be distracted by the bigger picture. Being number three in the world seven years ago was probably a big deal. This time round we’ve learnt it’s largely irrelevant.”

The Six Nations, as compellingly unpredictable as ever, comes first and O'Connell stresses that Ireland's focused preparation has been drilled into them by Joe Schmidt.

“Joe is big on getting better week by week, game on game, championship after championship,” O’Connell says. “He’s very process-orientated. We came into camp for a few days over Christmas and you’re expecting a review of the autumn and a preview of the year ahead. But we just got a plan for Italy. That was his way of saying: ‘If you’re involved with Ireland now, don’t look beyond the next game’. That message has been stamped in the players’ minds. I know it’s a cliche, but it’s good for us.”

When Schmidt arrived, O’Connell admits that it was difficult to adjust to his intricate gameplans. “You’re asked to do a lot of very different things. There is a lot of detail in terms of the plays and how we execute them. So, initially, for your first few games, you’re thinking a lot on the pitch. And rugby is a game where you have to be physical and aggressive and it’s hard to do that if you’re thinking too much. But once these things become second nature, and you’re doing them subconsciously, you start executing them with more aggression, physicality and speed.

“Joe is a brilliant communicator and he’s very good at making complicated plays really easy to execute. It needs to be explained well and simply and you need a coach who can let you know that you need to do this – or else – without creating a negative vibe.”

Schmidt and O’Connell are similar in their ability to exude authority while remaining understated. Their combination has helped lift Ireland to new heights with a deserved Six Nations win last year. The final match, a narrow victory in Paris, coincided with Brian O’Driscoll’s last Test. There was something inspiring and moving in the way that the two old masters walked slowly around the Stade de France at the end as the rest of the Irish squad gamboled ahead of them.

“Look,” O’Connell says with a wry smile, “you get to pick up very few trophies. I consider myself to have had a relatively successful career but there have been some barren years. When you pick up a trophy you want to enjoy that lap of honour and pick out the faces in the crowd. When you’re asked to remember great moments in your career those are the ones that jump straight into your mind. Obviously there are loads of fun times in dressing rooms. But you remember picking up a trophy, seeing your parents in the crowd. That day, that night, is the time to enjoy it most.”

There was a much less glorious day last month when Munster and O’Connell’s interest in the European Rugby Championship was ended by a crushing 33–10 loss to Saracens. O’Connell did not play well and the margin of defeat was startling. “I think they’re a better side than us,” he says with typical candour. “We’re a young side and we have a long way to go and the gap was very big. Personally, it was a very poor game. I was really frustrated with myself and it was a very disappointing day – but, luckily, they have been few and far between at Munster.

“I’m old enough now to know you can’t dwell on it. It is easier to put it behind you because I see it for what it is. Less experienced guys can get caught up in the doomsday scenario. I know we’ve got a great culture, a very good group of players, great coaches, and everyone is eager to be successful at Munster. We just need to learn from those experiences.”

Munster hammered Sale 65-10 the following week and O’Connell had a storming match. His 4½-year-old son, Paddy, came into the changing room after the game. “We have little biscuits laid out and he was eating them. After about five minutes of biscuit-eating he looked up at me and asked who had won.”

Paddy O’Connell, clearly, has got his priorities right. His father and mother, Emily, also became parents to a second child three months ago. “We had a baby girl – Lola,” O’Connell says. “There’s a TV show . . .”

The huge lock looks a little bashful. “Charlie and Lola,” I say, having first read the same books to my own small children almost 15 years ago. “Exactly,” O’Connell grins. “Charlie’s the older brother. So Paddy came up with Lola as the name for his new sister. She’s great.”

As his family expands, it might be tempting for O’Connell to consider an end to his playing career after this tumultuous season. “I’m not really thinking about it,” he says, “and I honestly don’t know whether this will be my last Six Nations. I haven’t made a decision either way yet.”

Does O’Connell know what he might do once he finally stops playing? “I have a few ideas but I’m not 100 per cent clear. It’s a bit worrying – but it’s also quite exciting. All I know is that when I do retire I will take a proper break. And then the most important thing is to find something that doesn’t feel like a job. That’s the way I am now. If I had a choice I would train every day of the week, do video, do preparation. I love what I do and it’s important to find that same passion.”

O’Connell is enthused by all he has learnt under Schmidt; and it’s easy to imagine him becoming a leading coach. “Yeah, I’m very interested in coaching and how we communicate. The best coaches seem to be very good communicators and they understand how people learn. So, yes, coaching is a possibility.”

A triumphant Six Nations, with games at home against England and France, followed by a successful World Cup, is just as possible. O’Connell’s face cracks open in a wide smile as he relishes his immediate future. “Apart from a few bumps and bruises I’m on an injury-free run – unlike the last few seasons. I’m contracted until the summer of 2016. So I’ve got some time and it certainly helps that this is a World Cup year. That makes it particularly exciting and it’s probably why I’m enjoying rugby more than ever.”

(Guardian service)