Eddie O'Sullivan says that Andy Farrell faces a challenge as he takes up the position of head coach for the first time when he replaces Joe Schmidt next year.

Schmidt's departure from the position with Ireland after the World Cup was confirmed on Monday, with Farrell moving up from his current role as the team's defence coach to replace the New Zealander.

Speaking on RTÉ's Against The Head, the panel noted how Farrell has made a successful transition from Rugby League into Rugby Union with Bernard Jackman also pointing out that the players 'speak incredibly highly' of the 43-year-old.

However, fellow panellist O'Sullivan said that taking on the top job with the Ireland team will bring a significant challenge for him.

"The one place where the transition has happened from Rugby League to Rugby Union has been in the defensive arena," O'Sullivan begins.

"That seems to be the pathway from Rugby League but the game has changed. Defence has changed and the attack has changed. There's a different structure around the game.

"The challenge I suppose is that he's [Farrell] never been a head coach and head coaching is not all about coaching. It's about making sure that everything's in the right place at the right time. You're responsible for everything.

"If you're the assistant coach for defence, you're responsible for that. If you're assistant coach for the line-out [then] that's your area. Once you're head coach, you're responsible for that plus everything else."

Former Ireland head coach O'Sullivan countered that point by remarking that Farrell is a familiar face to both the players and the IRFU as well as having the advantage of working directly with Schmidt.

"He would have had to have a lot of endorsements from the IRFU for them to offer him a contract like that. They're obviously very confident.

"The one thing that there will be speculation on now is who will replace Joe in terms of their attack coach for Ireland? Probably the reason they want to keep that quiet is because the obvious replacement is in Leinster and Stuart Lancaster has done a fantastic job there. 

"If that was to come into the ether, that would disrupt Leinster. No doubt we'll get to speculate on that."