ALL-IRELAND SHC SEMI-FINAL CORK v KILKENNY Tom Humphriesprofiles the Cork full-back who,despite recent adversity, has been entrusted with the key position again against Kilkenny tomorrow

JUST A QUICK shuffle through hurling's more recent back pages. It is difficult to find a case of a player feeling quite so much heat as Diarmuid O'Sullivan is experiencing as he faces into work at Croke Park tomorrow. The Rock under the microscope. Granite or something more porous.

Early in the week the hurling world waited vigil for word of his demise or reprieve as if it were a death watch. The abiding image of O'Sullivan this year has been his forlorn walks from the field of play wearing the sloped shoulders of a dead man walking.

Mortality is tugging at his sleeve. Old enemies are smelling his blood. Things go around and things come around again. In 1997, in a Cork jersey for the first time in a championship Sunday, he coursed Niall Gilligan around the pitch in Limerick until the Clare man was withdrawn at half-time.

That summer minted O'Sullivan's reputation as a swashbuckler. In the All-Ireland under-21 of 1997 against Galway he was split badly after 10 minutes. The first blow left him needing stitches inside his mouth. With the second blow his temple issued a great geyser of blood and the best that could be done was to staunch it till half-time.

At the break Donal Óg (Cusack), his friend and distant cousin, gave a speech about doing it for Sully. He was getting to the rousing climax when the same Sully emerged from the medical room with a helmet made of bandage and a hurl ready for war again. Indestructible.

A few weeks ago Gilligan was back working in the shadow of the Rock and this time Gilligan did the cleaning-out. O'Sullivan took the walk to the bench. Speculation surrounded the Rock's future. Gilligan's plundering came after similar larcenies by Joe Canning and Lar Corbett.

Full back is a merciless position, played on the edge of a cliff and for high stakes. Tomorrow O'Sullivan has stacked against him the ongoing decay in his self-confidence, the corrosion of age and the might of Kilkenny, intent on their three-in-a-row.

"Full back is a tough position," says Jimmy Barry-Murphy who introduced O'Sullivan to senior intercounty hurling back in 1997. "One mistake and you can be found out. A corner forward makes a mistake and he goes on to the next ball. A full back sees his mistake go up on the scoreboard. Diarmuid is getting a hard time from fans and on websites and that is not easy to take. His confidence is low and he is no fool. He knows Kilkenny have fellas all of whom are match- winners. He is under pressure."

O'Sullivan is under pressure but those who have known him and coached him feel starting him tomorrow is the right decision. Firstly confidence is a replenishable commodity and secondly if the relationship between a full back and a goalkeeper is always one of interdependence O'Sullivan's relationship with Donal Óg Cusack is almost unique.

O'Sullivan and Cusack grew up and played together. Cusack was a diminutive forward in those early days. When they started on the under-12s Cusack was 10 years old and minute. O'Sullivan was eight-and- a-half but husky. They were sent off to Midleton CBS together and graduated to the divisional team, Imokilly, together while also winning a Harty Cup and contesting the colleges All-Ireland of 1995 together.

Their understanding of each other and the lengths they will go to cover for each other are not things to be lightly dismantled at the height of a season.

Harder to change too because of the form of one, James "Cha" Fitzpatrick. Most permutations of an O'Sullivan absence involved shifting Tom Kenny out of midfield where Jerry O'Connor is feeling the aches of the aged suddenly. Such a move could be as disastrous. Besides, O'Sullivan would be a hard man to remove from any team.

"He was always larger than life as long as I remember him," says Barry Murphy. "Even in 1998 (when at 19 he captained Cork to a National League and into the championship) he was an inspirational figure . . . Diarmuid was always a huge figure, always positive. That relationship he has with Donal Óg is very unique but Shane O'Neill and Brian Murphy, they like having Diarmuid around them, they like the set-up. It would have been very hard to change."

Ironically, Barry-Murphy inflicted the greatest disappointment of O'Sullivan's underage career. As a teenager, O'Sullivan was left out of Barry-Murphy's All-Ireland- winning Cork minor side of 1995, (while Donal Óg was selected). His reaction gives an insight into his trademark confidence.

"I know Diarmuid came into a trial we had in Páirc Uí Rinn and we didn't go with him," says Barry-Murphy. "He was only 16. Word got back he wasn't at all happy that we had gone without him. I don't think he believed for years that we actually went and won an All-Ireland without him!"

O'Sullivan himself blames politics for having missed out and always made the point he was playing senior for Cloyne at the time. Over his career those who have watched him never remember any seepage in his confidence in himself.

At the turn of the century football briefly seduced him and the affair took its toll on his hurling. Martin Comerford, in the National League final of 2002, sauntered in at half-time having taken 1-3 off "The Rock". Cork enlivened a fallow winter with a players' strike. By the spring Donal O'Grady had arrived as manager and O'Grady's early issues with O'Sullivan's voluptuousness saw the full back missing classes for some time. He knuckled down. By the All-Ireland semi-final of 2003 against Wexford he was back to himself.Barry-Murphy doesn't remember a time though when the full back's form dipped.

"I don't think he ever had too bad a spell, playing-wise. He has been an inspiration to so many - fans, players and mentors. It hits everyone at some stage and it has happened to Diarmuid but he has been so good for so long that nobody has ever bothered grooming another full back. He is an amazing fella. He plays for the jersey. He loves the drama and the big occasions. Myself included, we have never looked beyond him in Cork."

The diagnosis is O'Sullivan has been trying too hard. Born a year after Christy Ring passed on but in the blessed fold of land that is Cloyne, O'Sullivan was a prodigy. By 20 he had an All-Ireland senior medal in his pocket, jingling along with a pair of under-21 baubles. With Cusack he had led Cloyne back to senior ranks in 1997.

O'Sullivan stormed like a hurricane throughout the 2000 semi-final against Offaly. The following year he scored that iconic point against Limerick, emerging like a Panzer from his square and launching a howitzer from 100 yards. Ka-Boom! That monstrously aggressive full back was a different species to the worried form in the number three jersey this season.

"Diarmuid looks like a player not sure whether he should go or stay," says John Allen, who coached O'Sullivan and Cork to their last All-Ireland win. "A full forward moves out. What do you do when your confidence is in crisis? His confidence is down. He is over-attacking the ball, over-committing himself. He is being caught. When your confidence is down you are afraid to go more than a few inches in front of your player because you are afraid you won't get back in time if it breaks past you."

Allen and Barry-Murphy differ as to other contributing factors. Barry-Murphy believes Cork haven't been shutting players down out the field as efficiently as in recent years and the quality of ball being delivered inside would make life difficult for any full back. Allen says not too many outside players in the modern game have time to deliver perfect ball to the inside man anyway. The problem is confidence.

"Confidence is a huge part of full-back play. With Diarmuid it's chicken and egg. Is his confidence down because he is playing badly or is it the other way around?"

Both agree the crisis has been overplayed, that O'Sullivan wasn't technically too much at fault for Joe Canning's remarkably well-taken one-handed goal, for instance, but that the signs of crisis are evident in O'Sullivan's play. "He is trying to bat everything at the moment," says Allen. "Sometimes it works and sometimes it doesn't. He is thinking of the catch but hasn't the confidence. I'd say to Diarmuid he needs to be as negative as he needs to be against Kilkenny. He doesn't have to be coming leaping over the heads taking the ball into his hand, stepping clear and driving it 90 yards and getting the crowd behind him. He needs to keep the ball out of his man's hand. . . . . He needs to get back into the position where he gets a bit of confidence. He has been trying too hard. Wants that crowd behind him again. He needs to keep it simple, relax into it."

The next most accomplished full back in Cork is Killian Cronin who also plays for Cloyne and who wears the number three shirt for the club while O'Sullivan hurls these days at centre forward.

Cronin was around the Cork panel for a couple of years but as a busy, self-employed man didn't feel he had the time to devote to bench-warming. Recent underage full backs Alywin Kearney or Eoin Dillon lack the physicality O'Sullivan had at their age and will need nurturing. It is a worry too that decent players don't get left at full back for their clubs.

"Apart from the lack of options in the panel, playing centre forward doesn't do Diarmuid too much good," says Allen. "Cloyne were involved in a replay, a draw and then a third match in the five weeks before the Tipp game. Diarmuid was playing centre forward for those weeks and getting no matches at full back."

So it comes down to tomorrow. Both former managers believe O'Sullivan needs to play it very simple and not over-sell himself going for the big play that will get the crowd on his side.

"Gerald (McCarthy) is well able to coach him," says JBM. "But I would say keep it very simple. He'll know the Kilkenny players inside out, They will try to use the space around Diarmuid. If he is dragged out the field I'd let Brian or Shane move out, and leave Diarmuid cover the square. I wouldn't encourage him out the field."

Apart from O'Sullivan's tactical play the opening lines of the game will tell us much. "If he does well on the first ball he will survive I think," says Allen. "I don't think he has lost the speed. He has lost the confidence. If he does well early he will be okay. If he looks vulnerable in two or three situations I would say they will whip him off. He needs to avoid overcommitting himself and grow back into it."

The O'Sullivan garden outside Cloyne was built on a hill. The five brothers who would eventually grow and play together for Cloyne played on it. The rule was the older you were the further down the hill you started. The work was harder, the incline greater, your ability to cope was supposed to develop accordingly.

Diarmuid O'Sullivan, a legend on the lower slopes, needs that memory to sustain him tomorrow.