Celtic League Round EightStrange, isn't it, the way sport throws up some odd, almost illogical patterns. Leinster have a pretty decent record against Munster latterly, and Connacht can't buy a win over Munster, yet when Leinster and Connacht have locked horns in recent years it's become a far more competitive fixture than historically used to be the case.
Of course these trends become self-perpetuating as well. Perhaps Leinster have sometimes been a little too confident, or at any rate lacking that element of fear, when playing Connacht, whereas the westerners, who seemingly suffer from an innate inferiority complex when playing Munster roll their sleeves up confidently when meeting Les Bleus, perhaps because they've usually had a bigger smattering of former Leinster players.
Maybe there's just no logical explanation.
Having once gone 30 years without a win against Leinster, seven of Connacht's 11 competitive victories in the fixture have come in the past dozen years.
Granted, they've only won once in nine visits to Donnybrook, though they've usually been close affairs, and that stunning 26-23 victory two seasons ago not only ended 17 years of hurt but also Leinster's 17-match unbeaten run at the D4 venue.
Mark McHugh's 83rd-minute drop goal was the difference between Connacht making the quarter-finals from the pool stages and thereby wresting away Leinster's hold on the trophy.
The near capacity crowd was also, assuredly, the biggest for a fixture between the two provinces and given the absence of TV cameras tonight (a first this season?), Connacht's expats being largely based in the capital and the return to Donnybrook's Friday night schedule, this could be another surprise hit.
Both sides come into this fixture on a high, Leinster having scored two wins in the European Cup to leave themselves well positioned for the resumption in December, while last week Connacht brilliantly overturned a 15-point, first-leg deficit against Narbonne to earn a second-round European Challenge Cup meeting with Montpellier.
This might seem, at first glance, like a step back toward more humdrum Celtic League fare but it's doubtful any of the protagonists will see it that way.
Even without their Irish squad members for the South African Test next week, Leinster can field a very strong side with up to half-a-dozen internationals.
Most will be chomping at the bit, especially the likes of Ben Gissing, Des Dillon, Felipe Contepomi and Christian Warner, and pretty much all of them will be keen to remind the Leinster think-tank that they backboned the four-match unbeaten start to this competition.
However, the subsequent defeats away to the Dragons and the Ospreys has seen Declan Kidney's team drop to third in the table, a dozen points off the Ospreys' pace. With the top two also meeting, this is an opportunity to regain lost ground. For Connacht, currently fifth, the prize is to go third in table and, for a day at any rate, become Ireland's highest placed province.
However, Leinster have regained some of their old Donnybrook swagger.
Unbeaten in seven games at the venue since early March, they ran in 10 tries in those aforementioned recent wins against the two Scottish teams, eight of them by the outside backs.
They were probably two of the most entertaining games on Irish soil this season and while the outside backs provided the cutting edge, it also required strong defence and forward play to subdue obdurate opponents.
Furthermore, while the celebrated O'Driscoll-D'Arcy axis may be missing, the possibility of Contepomi and Warner renewing the deft-handling midfield partnership last seen against the Borders is quite a prospect. Indeed, on a recent line through home games against the Scottish duo, Leinster would be 35- or 33-point favourites.
Not that Connacht will be of a mind to roll over and have their bellies tickled. Again overlooked even in the initial, 35-man Irish squad, and disadvantaged by their own Union (uniquely so in Europe) they'll have, as ever, a few points to prove.
After his remarkable exploits against Narbonne, and now that he has been named in the team despite injury doubts, Paul Warwick's presence will be a draw in itself.
But although Michael Bradley's decision to stick with the heroes of last week was entirely understandable, you'd have to wonder if Connacht can scale such heights again just six days later. That was a huge, win-or-bust game, an end in itself to some extent.
Their away record hasn't been great, that eye-catching bonus point win in Llanelli constituting their only win on the road in their last nine matches.
But then again, this isn't a particularly long road to travel.
LEINSTER (possible): J Norton; J McWeeney, C Warner, F Contepomi, G Brown; D Holwell, G Easterby; E Byrne/P Coyle, G Hickie, R Nebett, B Gissing, L Cullen, A McCullen, D Dillon, S Jennings. Replacements (from): D Blaney, J Lyne, C Potts, J Heaslip, N Ronan, B O'Riordan, B O'Meara, D McAllister, K Lewis, D Hewitt.
CONNACHT: M McHugh, M Mostyn, D Yapp, J Downey, C McPhillips, P Warwick, C Keane; R Hogan, B Jackman, S Knoop, A Farley, C Short, M Swift, M Lacey, J Muldoon. Replacements: J Fogarty, D McFarland, M Carroll, P Neville, C O'Loughlin, E Elwood, T Robinson.
Referee: Nigel Williams (WRU)
Overall head to head (since interpros introduced in 1946-47): Played 62, Leinster 47 wins, Connacht 11 wins, 4 draws.
Last five seasons: (99-00) Leinster 22 Connacht 19, Connacht 8 Leinster 53. (00-01) Leinster 21 Connacht 15, Connacht 22 Leinster 20. (01-02) (Interpro) Connacht 20 Leinster 49. (02-03) (CL) Leinster 23 Connacht 26. (03-04) Leinster 21 Connacht 6; Connacht 35 Leinster 24.
Five-game form guide: Leinster: (CL) 13-34 v Dragons (a); 35-13 v Edinburgh (h); 3-11 v Ospreys (a); (EC) 25-9 v Treviso (a); 30-11 v Bath (h). Connacht: (CL) 29-27 v Borders (h); 29-21 v Llanelli (a); 24-35 v Edinburgh (h); (ECC) 11-25 v Narbonne (a); 40-21 v Narbonne (h).
Leading points scorers: Leinster: David Holwell 37, Brian O'Meara 23. Connacht: Paul Warwick 87, Eric Elwood 21.
Leading try scorers: Leinster: Gary Brown, Denis Hickie 4 each, James Norton, Shane Byrne 3 each. Connacht: Paul Warwick, Conor McPhillips, Conor O'Loughlin 3 each.
Forecast: Leinster to win.
Also playing: Newport-Gwent Dragons v Neath-Swansey Ospreys, Rodney Parade, 7.05pm live on BBC Wales; Glasgow Rugby v The Borders, Hughenden, 7.30pm.
