If it seems a long, long time ago, it's because it was.
It was back in 2001 when Leinster and Munster went head-to-head in the inaugural Celtic League final, with the eastern province prevailing in a 24-20 Christmas cracker - despite being reduced to 14 men following a first half red card for Eric Miller.
As well as being a campaign that yielded Leinster's first major trophy of the professional era, it also featured another notable stat - the longest winning streak to start a northern hemisphere club season in the professional era.
Leinster won seven of seven in the Celtic League regular season, claimed three victories in the knockout stage and won their first five European pool games before finally falling to defeat away to Toulouse.
15 games and 15 wins to start the season.
Some teams have threatened to better it subsequently, but none have managed it. Saracens won their first 11 games in both double-winning campaigns of 2015/16 and 2018/19, while Harlequins went one better to start their Premiership-winning season of 2011/12.
Today, Leo Cullen's Leinster team are a perfect 12 wins from 12 this season; eight from eight in the PRO14 and four from four in Europe.
They have averaged over 36 points a game, five tries per match and have completed 87% of their tackles; impressive numbers, but could it eventually lead to the most impressive of all - a 100% winning record and the first northern hemisphere perfect season?
The hemispherical distinction is noteworthy because in 2002, the Crusaders managed to win all 13 of their games en route to the Super Rugby title - but this would be an entirely different achievement.
For Leinster to run the table would require 19 more victories than the Canterbury outfit needed, across two competitions while using roughly 50 players.
Maintaining interest on two fronts is something Cullen and his coaching staff are used to, having appeared in both the domestic and European finals in the last two campaigns. So could Leinster actually win every single game they play this season?
Well to start, the next leg on the journey is arguably the toughest road trip of all - Munster in Thomond Park.
And while Leinster go into battle in Limerick without their World Cup contingent - so too do the hosts.
One reason the prospect of a perfect season is not only being discussed - but also still a prospect at all - is because Leinster's second-string have been so good thus far. What looked to be difficult trips to Connacht and Glasgow merely served to reinforce just how deep Leinster can go into their squad and still produce seamlessly authoritative displays.
That's not even getting into the ruthless destruction of then-Premiership leaders Northampton, who were steamrolled in Franklin's Gardens with the big guns back in situ. So daunting away days are something that Leinster routinely negotiate regardless of personnel.
So what's the path to a perfect season?
Winning the double would be the bedrock - something this group have already achieved in 2017/18, so they know it is possible - but to not let standards slip across an entire campaign would require a focus and effort that heretofore no other team has ever managed.
Former Leinster star Luke Fitzgerald thinks that the pressure of completing an unbeaten season would become extremely intense as the campaign progressed.
"That game in Glasgow was a tricky one and they won in Benetton as well," Fitzgerald said.
"That has become a tough place to go. You'd nearly rather it wasn't something that was building because it can become a noose around your neck. You'd almost rather lose one so it wasn't talked about. The Patriots had a perfect season one year and then lost in the Super Bowl."
Looking down the line, were Leinster to round off their European group and PRO14 regular season as top seeds, as appears likely, they would then be facing a 20-game gauntlet featuring 10 homes matches, eight away ties and two at neutral venues, which would be the finals of the Champions Cup and PRO14.
Aside from the obvious difficulties posed by five potential knockout ties against the best teams in Europe, other tough games on their schedule include the impending trip to Thomond, a long-haul journey to South Africa to face the Cheetahs, who trounced Munster and Ulster there, and a regular season finale away to the northern province, while Leo Cullen's side will also host Munster and Glasgow in the league.
An extremely difficult task, no doubt, but there is an intangible element to it that works in Leinster's favour. Cullen, in effect, has a dual-mandate as head coach: the top-line is to win the Champions Cup and PRO14 every season, but beneath that is an almost entirely different goal, which is to lay the foundations for future success and cultivate the young talent that is the envy of every other club team in the world.
Not many set-ups could execute both so successfully and ironically, it is the latter, rather than the former, which could propel the province to perfection.
Just like in Glasgow, where Leinster's PRO14 record at Scotstoun was atrocious prior to this season, the young players were so determined to make the most of their opportunity that they raised their game substantially to match the challenge posed to them.
Were Leinster to go 32-0 and achieve perfection, it will be the days where the next generation of stars are tasked with earning their place that will be both underrated and integral.
Marseille and Cardiff host the two biggest games of Leinster's season, but if they want to achieve invincibility, it could be the second string's trips to Limerick, Bloemfontein and Belfast that prove vital.
Leinster 2019/20 Results and Fixtures
*Denotes TBC fixtures
32-27 Benetton (A) PRO14
53-5 Ospreys (H) PRO14
40-14 Edinburgh (H) PRO14
3-0 Zebre (A) PRO14
50-15 Dragons (H) PRO14
42-11 Connacht (A) PRO14
33-19 Benetton (H) Champions Cup
13-6 Lyon (A) Champions Cup
23-10 Glasgow (A) PRO14
43-16 Northampton (A) Champions Cup
50-21 Northampton (H) Champions Cup
54-42 Ulster (H) PRO14
Munster (A) PRO14
Connacht (H) PRO14
Lyon (H) Champions Cup
Benetton (A) Champions Cup
Cheetahs (H) PRO14
Ospreys (A) PRO14
Glasgow (H) PRO14
Cheetahs (A) PRO14
Kings (A) PRO14
*Champions Cup quarter-final
Zebre (H) PRO14
Munster (H) PRO14
Dragons (A) PRO14
*Champions Cup semi-final
Scarlets (A) PRO14
Cardiff (H) PRO14
*Champions Cup final
Ulster (A) PRO14