Jonathan Davies with the British and Irish Lions: Living the dream after replacing a hero

Welshman once asked for Brian O'Driscoll's shirt as a souvenir, but now he is quietly confident with taking his position for the series decider

When Wales beat Ireland in the quarter-final of the last World Cup, in New Zealand a little over a year and a half ago, Jonathan Davies' first instinct was not to embark on a lap of honour, or phone his family, or head for the bar. The one thing he really wanted was Brian O'Driscoll's shirt as a memento. Little did he suspect that here in Australia, ahead of the biggest game of the rugby year, he would lay hands on the great Dubliner's jersey for a second time… and end up wearing it instead of him.

Davies recounted the World Cup story in this newspaper back in March, shortly after he had played a leading role in bursting England's Grand Slam bubble and helping his country to another of their regular Six Nations titles. "I was still a little in awe of him, even then," he recalled, "so I thought it would be nice to have his shirt as a souvenir. Brian was doing media, so I stood there waiting for him like a supporter, which, in a way, I was. When the moment came, he said, 'No problem' and we swapped. I was pretty chuffed."

If he was "chuffed" then, he must be in a state of bliss right now. Certainly, it seemed that way. While the full-force gale over O'Driscoll's demotion from the Lions side for Saturday's climactic meeting with the Wallabies was continuing to blow through Ireland, with everyone from Willie John McBride to Martin McGuinness gusting away with the best of them, the quiet Welshman breezed through an intensive interrogation with a remarkable degree of calm.

Having spent more minutes on the field than any other Lion in the party and played out of position in a make-do-and-mend Test partnership with O'Driscoll, the 25-year-old Scarlets midfielder – born in Solihull but raised from a very young age in Bancyfelin, a village just to the west of Carmarthen – has been one of the tour's obvious successes. All the same, did he even begin to imagine that he might play all three Tests?

"That was the dream," he said. "Beforehand, everyone was talking about this being the best rugby environment you could experience, and it's lived up to that for me. It's been shown how important the Lions are to everyone in the game and I feel humble to be a part of it. But the main thing from a player's perspective is delivering under pressure, and that's something I've been working on over the last few years. It's slowly coming together. I'm reasonably pleased with the form I've showed but I want to keep pushing myself forward. What I want most of all, right now, is to finish the task we've set ourselves."

Unlike O'Driscoll, who had already been told he was out, Davies did not know he was in until Warren Gatland, the head coach, revealed his hand before Wednesday morning's training session on the Sunshine Coast, north of Brisbane. "I'm not sure if everyone in the squad was shocked when the team was named; I was just glad to get the nod," he said. "What struck me most was the attitude in training from the players who weren't in the squad and wouldn't be involved, which was obviously a huge disappointment for them.

"They're the ones who make the sessions, who do as much as anyone to prepare us as a team. If they can deliver a high standard having learnt that they're not playing, those who have been picked have no choice but to work at a high standard, too. Brian has been such a big part of that. He may not like me saying this, but I grew up watching him play and admiring his rugby. To play against him, and now to have played alongside him, has been wonderful. He has my respect."

While Davies understood completely that most of the discussion about his selection would have its genesis in O'Driscoll's omission – "I did expect a few questions about it," he said with a grin, "it just shows how good a player Brian is" – his new understudy, Manu Tuilagi, showed few signs of recognising that anything dramatic had happened at all. The human bowling ball had not been particularly tense during the build-up to the team confirmation, and could win his first Test cap of the series from the bench.

"For me, I just woke up, went straight into the meeting room and they announced it," Tuilagi recalled with what amounted to a verbal shrug. "I didn't hear anyone else's name but my own. I didn't even know who else was in the team. This is the biggest match of my career, but I won't put any added pressure on myself. I'll play my normal game and try to make an impact. After my second game in Australia, when I injured my shoulder, I thought my tour was over. I thank God that I'm still here. That's why there's no pressure. It's a rugby match. You can't think too much about it."

We can rest assured that O'Driscoll is thinking about it, every waking minute. We can also assume that just at the moment, the Irishman does not feel like laughing at any of Tuilagi's wisecracks. (Along with his fellow ultra-reticent South Sea Islanders Mako Vunipola and Toby Faletau, the English Samoan has been on "joke of the day" duty since the start of the tour. As he has about as much in common with Bob Monkhouse as he does with a seven-stone weakling on an Atkins diet, the mind boggles.)

Whether the Lions are laughing with him or at him, Tuilagi will be deadly serious on Saturday. Not as serious as Davies, though. If his new Lions- old Wales centre partnership with Jamie Roberts can just find a way of asking the odd unanswerable question of Christian Leali'ifano and Adam Ashley-Cooper, all is not lost for the tourists. And if Davies can see off a figure as significant as Brian O'Driscoll, who is to say he will not find a way past a couple of Wallabies?

Davies' details: Jonathan's tour

Jonathan Davies has played in six games on the tour (five starts) for a total of 423 minutes – the most by any player. He scored tries in three of his four warm-up appearances.

In all tour games

Tries 3 (second most of Lions players)

Carries 55 (third most)

Tackles completed 17 (third most)

Metres gained 270 (fourth most)

Offloads 6 (fifth most)

Test stats, Davies v O'Driscoll

Davies has made 14 carries for 42m, 17 tackles and three missed with five kicks and three passes.

O'Driscoll has made nine carries for 26m, 23 tackles and none missed, with two kicks and nine passes.