Leinster make up Pool 3 of the Champions Cup along with Wasps, Castres and Harlequins. They begin their campaign against Wasps on Sunday at the RDS.

Will O’Connor back Madigan at 10?

Jimmy Gopperth has endured a difficult start to the season at out-half for Leinster, and while their problems haven’t solely rested on his shoulders, the clamour for Ian Madigan to be backed at 10 from here on in continues to grow.

Will Madigan be the Leinster 10 moving forward? Source: Inpho/Billy Stickland

The 25-year-old has impressed fleetingly in the centre and lined out at fullback against Munster two weekends ago, but out-half remains his strongest position. His strong outing against Zebre on Saturday will have helped his cause.

Admittedly, Madigan was not at his peak at times last season, although it is notable that he lined out at 10 when Leinster put in their strongest performance of O’Connor’s reign so far in the 40-7 hammering of the Northampton Saints in Franklin’s Gardens.

Leinster now have stronger options in their midfield with Noel Reid back and Ben Te’o in Ireland, meaning Madigan may be freed up to return to 10 for the remainder of the season.

Who fills in for O’Brien and Healy?

The absence of Leinster’s two leading ball carriers is an obvious blow and O’Connor will need others to step into the void in attack. Rhys Ruddock has already been highlighted as the main man in that regard, and his ever-growing power will be useful.

Cronin has had a strong start to the season. Source: Inpho/Billy Stickland

Sean Cronin has made major inroads into the gainline in recent weeks, and looks like being an important ball-carrying figure too. The introduction of Te’o would provide Leinster with a destructive weapon a little wider out.

The truth is that O’Connor doesn’t have another player of O’Brien’s ability or anyone quite like Healy. At loosehead, he does have a superb player in Jack McGrath though, a prop who is stronger than Healy in areas other than carrying.

As the Australian coach himself has acknowledged, he may be forced to make tactical tweaks with O’Brien and Healy missing, but there is enough quality within Leinster’s group to compensate.

Does Luke Fitzgerald have a role to play?

Staying on the topic of injury, Fitzgerald’s recovery remains uncertain. Having the wing fit again would be a major attacking boost for O’Connor’s side, given the 27-year-old’s game-breaking abilities.

Fitzgerald has the X-factor Leinster need. Source: Dan Sheridan/INPHO

Leinster appear uneasy taking risks under O’Connor, particularly in running the ball from deep inside their own half, meaning they sometimes lack the ability to surprise opposition defences.

That element is exactly what Fitzgerald provides, as the Ireland international demonstrated in the middle third of last season. Oftentimes when he was fit, Fitzgerald’s half breaks and clean busts were what sparked Leinster’s best attacking passages.

Getting Fitzgerald healthy and back on the pitch as soon as possible looks a priority if Leinster are to top Pool 2.

What challenge will Conor O’Shea’s ‘Quins offer?

Following Premiership semi-finals in the last two seasons, as well as their 2011/12 title, Conor O’Shea’s Harlequins have been unconvincing in the opening month of the current domestic campaign.

O'Shea's 'Quins are thrilling to watch at their flowing best. Source: James Crombie/INPHO

That said, O’Shea’s men play a superb brand of risk-taking attacking rugby when they get into stride, and it seems likely their form will have improved by the time the December double-header against Leinster comes around.

It will be intriguing to watch those back-to-back games, as the former Leinster fullback looks to beat his old province with a game plan that would perhaps be more suited to the tastes of some of the RDS faithful than what they’re currently viewing.

For O’Connor, the chance to prove that his coaching ability has been underrated will be exciting.

Are Castres interested?

The perennial question surrounding the Tarn-based side. Castres’ form in the Top 14 has not been impressive early this season, although the fact that they have reached two consecutive finals in the French league suggests they can bounce back.

Leinster beat the French side twice in the Heineken Cup last season. Source: Morgan Treacy/INPHO

When it comes to Europe, it’s hard to know what kind of team Serge Milhas and

David Darricarrere are going to select, as well as how motivated the players are actually going to be.

This competition, in its former guise as the Heineken Cup, simply didn’t capture the imagination of Castres’ fans and playing staff. If the new format ignites them, then the likes of Rory Kockott, Richie Gray, Rémi Tales, Rémi Lamerat and Johnnie Beattie could cause Leinster serious problems.

O’Connor won’t be discounting the challenge of Wasps in rounds one and six, but if his Leinster side can’t beat the team who were the final qualifiers into this season’s Champions Cup, they will be in major trouble.