Dragons and daggers drawn in Dublin: Fear and loathing among the Celts

A host of bitter, personal feuds means the Croke Park air will be thick with enmity when Warren Gatland arrives with his Wales side to tackle Eddie O'Sullivan's Ireland tomorrow

Here is how it goes. Warren can't stand Eddie; Eddie doesn't much care for Warren; Brian dislikes Gavin; Gavin feels the same way about Brian; and "old Melon Head" foams at the mouth when coming across most things green. If ever there was a grudge match in professional rugby then Saturday's visit of Wales to Ireland is it – with a capital "GRRRR".

Yes, the needle will fly at Croke Park, in as many directions as the conga at the Dublin knitting circle's annual awards dinner. Believe it, the animosity runs from top to bottom between these two sides. And it hardly dilutes in its venom on the way down.

Best start at the apex of this disaffection. Warren Gatland and Eddie O'Sullivan were once boss and assistant in the same way that Blair and Brown were once boss and assistant. Except Gatland and O'Sullivan were never, ever allies. There was never a meeting at a trendy eatery and, thus, there was never a "deal" . It was much more straightforward than all that. The latter wanted the former's job and the latter eventually got it. At the expense of the former, naturally.

The scene was the Berkeley Court Hotel, just across the road from Lansdowne Road, and the date was Wednesday 28 November 2001. As Gatland turns left out of the car park, shell-shocked at the P45 lying on the passenger seat, O'Sullivan drives past Gatland at the car park entrance. Despite winning nine of his last 11 matches Gatland has just been told, in an eight-minute meeting, that his contract as Irish coach will not be renewed. A little later O'Sullivan signs his three-year deal.

To say that the atmosphere between the pair since has been "frosty" is only non-factual because there hasn't been an atmosphere. While Gatland went chalking up his streak of Ws – Wasps, Waikato and now Wales – O'Sullivan stayed put, leading Ireland through the most successful patch of their history. Not once did the duo meet or make contact with each other. "I haven't seen him in six and a half years and I spoke to him for about 30 seconds during the Six Nations launch [in January]," said O'Sullivan on Tuesday. Some bystanders at that brief encounter confirm that this was approximately 30 seconds too long for Gatland.

Evidence of the Kiwi's bitterness came in two interviews he did this week; the first on Sunday, when he confessed that he had been warned "not to touch Eddie with a bargepole", and the second on Wednesday when he was asked how he now felt about O'Sullivan's service under him. "On reflection what I didn't have was the undying loyalty you might expect from people within your coaching set-up," said Gatland, concerning the "partnership" that lasted 28 months. "That is what we have got here with Wales. Eddie is his own man."

In fairness to O'Sullivan, any Machiavellian manoeuvres he may or may not have made in the background as Gatland was being sized up for the chop were perhaps understandable. Here was a patriot from Co Cork who had to watch a young All Black first take his job at Connacht – when O'Sullivan was arguing for a long-term contract – and then, a few years later, assume the role he believed was an Irishman's by rights. Inevitably, Gatland did not see it in such tones of blessed emerald.

"At the time, as the team were going pretty well, I wasn't thinking who was going to try and win points, who was backing me, who's supporting me," Gatland said. "It was only when I left and looked back on all those things. For me, the most important thing wasn't about all that. It was about doing what I felt was best for Irish rugby. I wasn't dealing with the political things and making phone calls and ringing the president and ringing the chairman and getting them onside and ringing certain people in the press."

It is now widely believed that O'Sullivan did indeed plot a canny path through the Irish press towards the hot seat. In the Irish Times last Saturday, the respected rugby union correspondent, Gerry Thornley, mused that "on the day before Gatland's dismissal, two Sunday newspapers supportive of O'Sullivan ran a story that he had been offered a six-year deal to coach the USA Eagles". Meanwhile, in From There To Here, the excellent tome charting Irish rugby's transition into professionalism, the Irish Independent on Sunday journalist Brendan Fanning reveals that Donal Lenihan, the then Irish team manager, found cause to pull aside O'Sullivan. "After the win over Scotland [in 2000] O'Sullivan was picking up a lot of the kudos for the turnaround in fortune," Fanning wrote. "Lenihan launched into him one day, accusing him of covertly promoting his case on the media."

O'Sullivan brushed off such criticism and, although he retains the nickname "The Dagger" in some quarters, he did so largely successfully. Yet to Gatland the stench of disloyalty clearly lingers. "It was my choice to appoint Eddie," he said. "But the number of people who said: 'Don't touch him, don't go anywhere near him, don't touch him with a bargepole' was huge. But you have to back your own judgement about people and their ability. I did that and sometimes in life you get burnt."

Those scars did heal incredibly quickly, though, as Gatland now acknowledges. "When I left Ireland I had eight job offers in the space of two weeks and one of them was the opportunity to go to Wasps," he said. "That proved a great decision. I am quite happy with the way my rugby path has gone."

Nevertheless, he would be happier still if that path continued to lead him onwards and ever upwards and who knows, even impeded O'Sullivan on its way. Over To George Hook, the outspoken Irish pundit who gave Eddie O'Sullivan his first break at Connacht before eventually falling out with his prodigy. "Warren still wears on his sleeve the feeling that he was shafted by the Irish Rugby Football Union and by Eddie," Hook said. "O'Sullivan is the kind of guy where the stiletto enters between your second and third intercostal. Gatland is more of a bludgeon over the head down a dark alley kind of guy. They will hate each other until their dying day. The results on Saturday will be just as much a personal victory for them as the men in green or red."

Point taken, although, as always with rugby, it will be decided on the pitch rather than in the stands. Fortunately for lovers of a good old Blarney, the enmity will surely bristle just as spikily between the whitewash. "It's not just a thing between the coaches – although that is pure animosity – as, with an honourable few exceptions, the two sets of players don't like each other," said one Welsh insider. "Our boys think the Irish are arrogant and, by all accounts, the Irish think we're overrated. The majority of the bad feeling probably goes back to 2005 and that Grand Slam afternoon."

It was in the 10th minute of that famous Millennium afternoon as O'Driscoll followed up a tackle on Henson when the fuse was first lit. "As I was on the ground, O'Driscoll came in and tried to 'jackal' me – a term we use to mean stealing the ball from your opponent," wrote Henson in his controversial My Grand Slam Year. "But he also decided to pull my hair and tried to gouge my eye for good measure, saying, 'How do you like that?' There was a real flash of anger in his eyes. It was intense. I still don't know what wound him up. It may have been something I'd said in the build-up."

Whatever that might have been, O'Driscoll was certainly wound up in the aftermath of Henson's book launch, especially as, by then, he had appeared on a Lions tour with his fellow centre. "I don't think you do yourself any favours by giving it out about team-mates in a book, rather than saying it to their face," O'Driscoll said. Flash point No 1.

Not that there was any great outpouring of support for Henson in his own Welsh set-up – after all, he had a go at most of them in his delicious book, too – but neither did they rally around O'Driscoll. The truth is that, because of the close contact they had been sharing together in the Celtic League, the Irish-Welsh rivalry had been building and building. There was another incident on Wales' victorious afternoon which confirmed this.

While O'Driscoll's alleged attack went unnoticed to the naked eye, Gethin Jenkins's grand-slam dunk could hardly fail to. It wasn't the prop's try that signalled his intent so much as his celebration. On touching down, Jenkins – nicknamed "Melon Head" because of his skull's similarity to a certain fleshy fruit – leapt to his feet and threw the ball at Ronan O'Gara, the fly-half whose kick he had charged down for the score, mouthing something along the lines of "fucking have it" in the process. So what should have been a moment of unbridled joy became an instant of sheer aggression and said everything one needs to know about the relationship between the two teams.

"That game lives in the memory, certainly of our lads," said the insider. "They felt like they proved a point that afternoon about how underrated they are and feel they can do so again this weekend, after some torrid beatings in Ireland. No, there still isn't any love lost between O'Driscoll and Gav, but there's quite a few other fierce rivalries. This isn't just about Warren and Eddie. Granted, it's about winning a rugby match and the resulting silverware. But it'd be all the sweeter because of who the opponents happen to be."

So much for Celtic cousins. With relatives such as this, who needs the English?