Leinster facing a crucial crossroads as they host Harlequins

Befitting the weekend's biggest attendance by some distance, this is simply huge. The ramifications of tonight's encounter at the Aviva will ripple for months to come. This return summit meeting between the leading two in Pool Two could well determine qualification for the last eight of the Champions Cup and much else besides.

Were Harlequins – one of only two teams with three wins from three – to make it four from four, they would be virtually certainties to reach the last eight, while Leinster would almost certainly slip to third in the group given Wasps host a Castres outfit who have predictably lost interest already.

By contrast, were Leinster to win, they could regain leadership of the pool and with it control of their destiny, but to do so they would need to emerge from these back-to-back meetings with a superior head to head record over Harlequins.

Two matches

In the event of two sides from the same group finishing level, their standing will be determined by the head-to-head record, and firstly match points followed by tries scored in the two games and then the aggregate points’ difference from the two matches.

Leinster’s bonus point at the Stoop last Sunday could thus prove invaluable, although to ensure they finish ahead of Quins on head-to-head they would thus need to deny the Londoners a bonus point – thereby earning five match points to four – or score a bonus point themselves.

Given Quins scored two tries to none last week, a bonus point defeat for them could thus give Conor O’Shea’s team an edge unless Leinster outscore them by two or more tries.

The notion of Leinster scoring four tries may seem fanciful but they appear to have sharpened their cutting edge with the inclusion of Zane Kirchener on the right wing, with Luke Fitzgerald moving to outside centre in the absence of the injured Gordon D’Arcy and Darragh Fanning switching flanks.

Kane Douglas, who added to Leinster's carrying game when introduced last week, and the in-form Dominic Ryan also return to the line-up, while more contentiously Matt O'Connor has opted for Isaac Boss at scrum-half with Eoin Reddan to provide a change up in tempo off the bench for the final 20 or 30 minutes.

Reddan is certainly equipped to do that but even allowing for his curiously off-colour performance last week, there would have been merit to having his zippier service from the off to maximise the running, creativity and footwork of Ian Madigan, Fitzgerald, Kirchener etc.

Interestingly, Heaslip said of O’Connor yesterday: “Over the last two years Matty has really opened up our game, forced us to maybe play more and not be as robotic, to use your football ability while still working in a system and the way we want to play.”

Yet if Leinster are to fully utilise the benefits of an Aviva pitch wider than the Stoop, Jimmy Gopperth will need to replicate his aggressive first-half performance from last week when taking the ball to the gain line – rather than the more muted second-half effort.

As expected, with the hugely influential duo of playmaker cum goalkicker Nick Evans and chief standard-bearer Chris Robshaw ruled out earlier this week, Tim Swiel makes his first start at outhalf, with Jack Clifford named in the back-row. Quins can afford to swing from the hip, and Heaslip nodded vigorously in agreement when O'Connor suggested O'Shea's team will be better this week.

“We’re genuinely expecting them to be better. They’ve given themselves a chance. The winner of this game goes a long way towards winning the group and is in control of their destiny and the quarter-final, then you’re in a position to win the competition.

Player welfare

The IRFU player welfare programme must undoubtedly frustrate the provincial coaches, and coupled with their sizeable injury list has added to the strain on Leinster’s resources. Yet this could be an example of where it will work to one of the Irish province’s benefit.

Robshaw is assuredly paying the price for having had to play all 80 minutes on four successive Saturdays captaining England at Twickenham before completing the full 80 despite his shoulder injury last Sunday.

English loose-head Joe Marler was also in obvious discomfort, and mindful that Romain Poite tends to go with the scrum which is inching forward, however they achieve the feat, Leinster will be acutely mindful of avoiding the embarrassments of last week.

Indeed, they should have every motivation in the world, what with their last two European defeats at this venue, the high stakes and the desire for redemption. “It’s about winning the game, that’s how we would put a right to wrong,” maintained Heaslip.It’s hard to believe they won’t.