Now or never was the motto surrounding Leinster heading into the 2008/09 Heineken Cup season.

Based in Ireland’s capital, Leinster’s relentless inability to emulate the success of their closest rivals, Munster Rugby, on the EPCR stage had become a rather taboo subject for those who supported the men in blue.

Yet, fourteen years later, Leinster once again sit on the crest of a wave as their ‘drive for five’ edges ever closer to a conclusion. Securing this fifth title would see Leinster join Toulouse atop the table as the joint-most successful side in EPCR history.

Pinpointing the exact moment where the change occurred may prove more difficult than many would anticipate. Built over years of struggle and demoralising failures, Leinster’s renowned hardened championship edge is one of the sport’s more fascinating journeys.

Possessing a squad stacked with talent, namely the majority of the Irish international backline, Leinster lacked the backbone of their gritty southern neighbours Munster. Stumbling time and again at the crucial stage, many wondered if their lauded ‘golden generation’ would ever get across the line.

Reverting to Churchill’s famous assessment of the Soviet Union in the wake of World War II - ‘a riddle wrapped in a mystery inside an enigma’ - few experts or fans could understand the direction being undertaken by the leadership brass at Leinster during the early to mid-2000s.

Six playoff appearances in fourteen seasons had all ended in defeat, with the greatest indignity being a 30-6 shellacking at the hands of Munster in the 2005/06 semi-final.

Second position in that season’s Magner’s League following a 40-31 loss to Welsh side Cardiff Blues in the penultimate round would add further salt to the wounds as they saw what look set to be their title drift northwards towards rivals Ulster Rugby.

Thus, the title of bridesmaids would become a tag that proved as difficult to shift as a 370lb gorilla.

A quarter-final exit and third place in the league the following season appeared to be the final nail in the coffin for the golden generation. With whispers emerging that several of their star players, most notably Brian O’Driscoll, were on the hunt for new challenges abroad.

Having taken the bold decision to hire an unknown quantity in head coach Michael Cheika in 2005, the Leinster brass spearheaded by Chief Executive Mick Dawson was under heavy fire.

Later describing the move as a “calculated punt” on the Australian, Dawson’s decision to bring in the former Randwick coach would eventually pay dividends.

Adding further credence to the notion that the world of professional sport operates in a cyclical manner, Leinster’s 2007/08 and 2008/09 seasons would be defined by their battles with two of their staunchest rivals.

A third-place finish in Pool Six behind eventual runners-up Toulouse and two-time champions Leicester Tigers would see Leinster crash out of the Heineken Cup before the knockout stage in 2007/08.

The unceremonious dumping out of the competition would significantly ratchet up the pressure on an already at-capacity pressure cooker surrounding the duo of Dawson and Cheika.

The dark clouds of despair engulfed Dublin once again. 200km south of the capital, many a champagne bottle was about to be uncorked as Munster were on their way to yet another semi-final appearance. The men in red would eventually go secure their second title in three seasons with a tetchy 16-13 win over Toulouse in a cauldron of intensity at Cardiff’s Millennium Stadium.

The Munster heroes led by Paul O’Connell, Anthony Foley, Ronan O’Gara and co were correctly heralded for their dogged ability to overcome fancied EPCR opposition. Leinster’s stars would again be licking their wounds, yet unlike seasons gone by this time, there was something brewing.

As the celebrations raged in Clare, Cork, Kerry, Limerick, Tipperary, and Waterford, focus was shifted in Dublin towards domestic competition and a real chance at silverware.

Securing a second-ever Magner’s League title in the 2007/08 season two weeks before the final of the Heineken Cup would see the wheels of change begin to turn at the Royal Dublin Society Ground.

Yes, their rivals down south had once again edged them on the biggest stage, but two league victories over Munster had firmly put to bed the psychological hangover of the 2005/06 semi-final.

Throw in the fact that they had edged Cardiff for the title, further dispelling any hang-ups surrounding a club that had cruelly ended their hopes two seasons prior. And one could see the foundations from which success would be built.

With a trophy now proudly on display for the first time since 2002, attention would switch from domestic success to leaving their mark in EPCR competitions.

Topping Pool 2 in 2008/09 ahead of English champions and two-time Heineken Cup winners Wasps was the first step of what would prove to be a turning point for the province.

Leading from the front, Ireland captain and talismanic figure O’Driscoll would top the try-scoring charts.

Yet, whilst the pool was topped, their position as the lowest-ranked pool winners would see them begin the knockout stage as the sixth seed. Thus, an away quarter-final to English side Harlequins would be on the cards.

That clash would become infamously known as ‘bloodgate’ due to an audacious stunt from Quins coach Dean Richards and wing Tom Williams. Aiming to bring back the previously substituted goal kicker Nick Evans, Richards sent the instructions to the sideline. With both men receiving lengthy bans in the wake of the incident, it is rather fortunate that Leinster edged the contest 6-5.

From here, the titanic figure of Munster would be awaiting them in a semi-final scheduled to take place at the famous Croke Park, the home of the Gaelic Games.

Still to this day, the highest attended club rugby match with 82,208 spectators in attendance, Leinster would stamp their authority on their southern rivals in ruthless fashion.

As O’Driscoll picked off his international pal O’Gara to sprint away for an intercept try in the 61st minute, the winds of change could be felt blowing through the hollowed grounds.

However, it was the emergence of one Johnny Sexton that would prove to be the biggest development for both Ireland and Leinster for the next 15 years.

Having taken the place of regular fly-half Felipe Contepomi, the Argentina international who had gone down injured early in the clash, Sexton finally had his chance to prove himself following three seasons in the Puma’s shadow.

As Sexton towered over O’Gara following Gordan D’Arcy’s opening try, a shift in power on a level unlike any in Irish rugby history had been established.

Sexton would go on to displace O’Gara in the Ireland starting team over the coming seasons, beginning what would develop into the greatest international and provincial career of any Irish player.

As the curtains came down at Croke Park with Munster in the unfamiliar position of watching their rivals progress to a final, Leinster would begin to plot their assault on the final to be played at Murrayfield.

Facing them would be two-time champions Leicester, who defeated Cardiff via a place-kick competition following extra time.

In what would prove to be a tense final, a 70th-minute penalty from Sexton was the difference between the two sides.

When legendary Welsh referee Nigel Owens blew the final whistle, a brief sigh of relief gave way to unadulterated joy with celebrations that would go long into the night.

The adage of fall seven times but get back up eight is particularly applicable to the current success Leinster are enjoying.

So often dealt the cruellest of blows, Leinster are now unequivocally one of the top three professional club rugby sides in the world. Rivalled only by New Zealand’s Crusaders and Toulouse, Leinster have gone on to win three more titles since 2008/09, including famous back-to-back triumphs in 2011 and 2012.

Once again this season, Leinster’s drive for five will face the monumental task of taking down the side they are chasing as the most successful side in the competition’s history in Toulouse.

Having cleanly dismissed their French foes last season in a 40-17 romp at the Aviva Stadium, Leinster are all too aware of the threat that a side looking for redemption pose.

Should Leo Cullen’s team see off their French opponents, it will likely set up a rematch of last season’s final with another French powerhouse in Stade Rochelais.

Ironically coached by Munster legend O’Gara, La Rochelle are the antithesis of Leinster.

Possessing a team physically bigger than just about any other in professional rugby, La Rochelle are a side that harkens back to the glory days of Munster.

Representing a small city by modern French standards, La Rochelle are the heartbeat of their community.

Fuelled by passion, physicality and moments of brilliance, La Rochelle play a less structured game, relying on big individual moments from their stars.

Leinster, on the other hand, operate from a nearly militant, organised and fast platform. Not to say they don’t have individual stars capable of breaking a game open, but they are side filled with talent who simply know their role inside and out.

Having lost last season’s final in the dying stages, in addition to their semi-final loss a season prior to the same opposition, Leinster will be seeking revenge buoyed by what should be a jam-packed Aviva Stadium.

Should Leinster overcome these two challenges, then their fifth star on the jersey could prove to be the most impressive of the lot.

As Leinster Rugby host Stade Toulousain in the Heineken Champions Cup semi-finals in Dublin at the Aviva Stadium on Saturday, our US broadcast partner FloRugby takes a look back at how the Irish province’s dynasty began.