For the first time in his Test career, Peter Stringer missed an international due to injury two weeks ago against France, but the diminutive scrum-half has proven his fitness for the game against England, having recovered from a fractured hand.

The return of Stringer to the Irish side  he will be starting in the half-backs alongside Ronan OGara for the 47th time  along with captain Brian ODriscoll, certainly solidifies a back line that failed to fire against the French.

And OSullivan is banking on the Munster number nine having a big influence on proceedings at Croke Park.

He explained: Its a big boost to have Peter back for a game like this.

Its a pivotal game in the Six Nations for us and this is the one you want to have a full deck for.

If we win were right back in the hunt again.

Peter is probably the best passer of the ball in the world at number nine - he gives the receiver so much time.

The odd one goes astray but when you pass the ball 60 or 70 times in a game theres going to be one or two off target.

He has a capacity as well to get us out of jail. Hes done that a couple of times in big games where theres been massive line breaks when you could see nothing but a try coming, and he comes out of nowhere and takes somebody down with a hand trip.

OSullivan continued: Its not the dog in the fight, its the fight in the dog with Peter. He does box well above his weight all the time.

He puts in a huge number of tackles and always tackles people that are bigger than him because theres nobody smaller than him on the pitch.'

Despite his 5ft 7in, 11 stone frame, Stringer cuts an authoritative figure behind the Irish scrum and his presence and experience - tomorrow will mark his 74th cap - will be vital in the heat of the battle.

O'Sullivan added: 'Hes a good organiser, he barks at the pack and keeps them in line and theyre all afraid to cross him and that dynamic is very important in a pivotal position.'