Van der Flier, Ringrose left out as Blues eye top spot
In a typical season for Leinster, their final Pro12 game before attentions turn to the climax of the Champions Cup pool stages would represent a dress rehearsal of sorts, but the importance of this evening's clash against the Ospreys far outweighs anything that is to come in the next couple of weeks.
Zero wins from their four games has left Leinster's European ambitions well and truly buried, but on the domestic front, there have been plenty of signs of rejuvenation in recent weeks - and they will go top if they win in Wales.
Leo Cullen's maiden season in charge of his home province now hinges entirely on what they achieve in the Pro12 but for tonight's opponents, their focus is not as straightforward.
The Ospreys currently sit top of their pool and although they may be overtaken later tonight, depending on the result between Bordeaux-Begles and Clermont Auvergne, they will nevertheless return to Europe next week with major ambitions of advancing to the knockout stages.
The reality of both teams' situations is reflected in the coaches' selections, with Cullen going almost full strength, whereas his opposite number Steve Tandy evidently has one eye on the visit of Clermont next Friday.
The most surprising of Cullen's six changes to the team who saw off Connacht last weekend is the omission of Garry Ringrose, not only from the starting XV but from the entire match day squad. A lot has been written and said about the 20-year old in recent weeks but the fact remains is that he is currently the form 13 in Leinster's squad and arguably in Irish rugby right now.
Given his performances against Munster and Connacht over the festive season and indeed his first inclusion in an Ireland camp earlier this week, Ringrose's confidence is sure to have been high but now he will presumably have to revert back to water boy duty, while the same can be said for the equally impressive Josh van der Flier, who is also left out entirely.
"We try to just bring Garry through slowly this season," Cullen stressed after the win over Munster.
"We want our young players to be able to play for Leinster for 12 to 15 years so that's an important part of it. There's a lot of games this season and we want to make sure that guys come through in the right manner."
With the two talented youngsters left out, one can only assume that they will feature heavily in the remaining two games in Europe, but both can feel hard done by.
Ben Te'o switches to outside centre, with Luke Fitzgerald returning to the side, while Luke McGrath is fit enough to take his place at scrum-half, giving Eoin Reddan a well-earned rest after a couple of very impressive performances of late.
Johnny Sexton has shaken off the knee injury that prematurely ended his involvement last time out and he will renew his rivalry with Dan Biggar.
The Wales out-half enjoyed an outstanding World Cup in comparison to Sexton, who admitted that being forced off against France was the biggest disappointment of his career.
Sexton and Biggar are set to meet again in Dublin when Ireland take on Wales in their Six Nations opener on February 7 and the importance of who comes out on top this evening cannot be underestimated.
The pair's heavyweight clash at the Liberty Stadium is sure to have a major say in which side continues their winning run but it is the battle in the back-row that many will be focused on.
Dan Lydiate misses out through injury, while Justin Tipuric starts on the bench alongside captain Alun-Wyn Jones - a clear indication of the Ospreys having one eye one Europe.
"Clearly the win over the Dragons last weekend came at a cost with some senior players ruled out of action but we can't look to hide behind that as an excuse," coach Steve Tandy insisted.
"Although it's a young squad involved, there's a hardcore of international experience still available and we've got some exciting up and coming talent mixed in who have a chance to really make a name for themselves, starting this weekend. They've got to thrive on the opportunity and make the most of it.
"Leinster had to deal with similar issues to ourselves at the start of the season due to their over-contribution to the Rugby World Cup but have more than made up for that as they've played their way towards the top of the table.
"We know that we have to continue striving for excellence as a team, working hard as a collective, if we're going to keep heading in the right direction ourselves.
"It's a relentless month and that's what we've got to be as a group now, relentless. If we aren't, we won't get what we want from these games," he added.
Tandy's options may be somewhat limited but for Leinster, Rhys Ruddock, Sean O'Brien and Jamie Heaslip make up a back-row that may well be the same one that starts for Ireland on February 7.
Ruddock is one of the form players in the country right now, and having missed the majority of the World Cup, he looks like he is back to his best.
Joe Schmidt will have several headaches when it comes to his back-row selection in a few weeks and you can be sure that he will be keeping a close eye on how the Leinster trio performs as a unit.
Tadhg Furlong returns to the starting XV and will make up the front-row alongside Jack McGrath and Richardt Strauss who is again preferred to Sean Cronin.
Having not been in Carton House with Ireland this week, Furlong will feel as if he has something of a point to prove ahead of the Six Nations campaign.
The Ospreys may have won five of their last six games but Leinster are also hitting form and without any European distractions to worry about, they shouldn't have any excuses not to leave Wales with what would be a priceless victory.
Ospreys - D Evans; J Hassler, J Spratt, O Watkin, H Dirksen; D Biggar, B Leonard; P James (capt), S Baldwin, A Jarvis; L Ashley, R Thornton; J King, S Underhill, D Baker. Reps: S Otten, N Smith, M Fia, A Wyn Jones, J Tipuric, T Habberfield, S Davies, E Walker.
Leinster - R Kearney; I Nacewa (capt), B Te'o, L Fitzgerald, D Kearney; J Sexton, L McGrath; J McGrath, R Strauss, T Furlong; D Toner, M McCarthy; R Ruddock, S O'Brien, J Heaslip. Reps: S Cronin, P Dooley, M Moore, T Denton, D Ryan, E Reddan, I Madigan, N Reid.
REF - D Wilkinson (IRFU)
Ospreys v Leinster, Live, Sky Sports, 7.45