Marcus Horan has been ruled out Ireland's game against Scotland in Murrayfield tomorrow after he suffered a calf strain during a run out in Edinburgh this morning. The prop will be replaced at loosehead by Ulster's Simon Best, whose provincial team-mate Bryan Young moves on to the bench.
The loss of Horan is a real blow to Ireland following the prop's performances in the tournament so far, against England in particular. Horan is one of the world's most mobile props and has scored five tries for Ireland in his 45 appearances at senior international level.
Best, however, is no stranger to this frontrow having been capped 14 times, and he will line out beside his brother, and Ulster team-mate, Rory.
Denis Hickie is another injury concern but the winger came through training this morning after suffering a back spasm in yesterday's session.
Leicester's Geordan Murphy was drafted in for cover but Hickie will be given every chance to prove his fitness. If he misses out Andrew Trimble will move from the bench to the left wing and Murphy will take his place among the replacements.
"Denis trained this morning and everything seemed fine, but obviously the problem with a back spasm is that it could go backwards again and if it does we could be in trouble tomorrow," said O'Sullivan. "We'll just have to see how he goes in the warm-up and I think we'll leave it to the last minute to be 100 per cent sure.
While Ireland, flying high after a spectacular victory over England a fortnight ago, will be aiming to claim the Triple Crown tomorrow, Scotland will be looking to salvage some pride after a 37-17 humbling by Italy.
O'Sullivan believes, however, that it would be dangerous to read too much into the background of this match.
"You buy into that stuff and it will be your downfall. The one thing we know about Test rugby is that all the talk that goes on before the match might be very interesting, but when the ball is kicked off nobody knows what is going to happen,' he said. "If you are going to depend on the past to win the game tomorrow then you are in big trouble.
"This Scottish team have a point to prove and we know that is all Scotland need - they have shown many times in the past that they are very good at proving points.
"And we've gone into games before where we've been favourites but been turned over because we probably bought into our own fame too much."
Scotland coach Frank Hadden is of a similar opinion. A fortnight after grabbing the rugby world's attention with an embarrassing home defeat Hadden insists that the Six Nations is a 'horses for courses' competition and that his underdogs are ready to upset the form.
"You can never, ever, be sure what the outcome is going to be. The Six Nations is such an exciting competition because all the teams are so different from each other, and you are never quite sure what is going to happen when they come together," he said.
"There is an uncertainty about the Six Nations which is part of the drama and the excitement.
"It's like when two boxers come together. Some boxers find it difficult against opponents that you would ordinarily expect them to find it straightforward against.
"So, we might be the underdogs against Ireland, but in a lot of the games we play we are the outsiders, and we definitely relish that role."
O'Sullivan found time today to speak up on behalf of Dan Parks, the Glasgow outhalf who has been much maligned in the past, but recalled for this game at the expense of Phil Godman.
"I know Dan Parks isn't too happy that he has been tagged as a kicking outhalf and it is very unfair actually," said the coach. "I would agree with him - but he is a very good kicker and the one thing they have got tomorrow is that this guy can rifle the ball 50 or 60 metres in behind you and pin you down.
"It wouldn't take a rocket scientist to figure out that this is something they will use at some point."
Ireland XV to face Scotland
15- Girvan Dempsey Terenure College/Leinster 72
14- Shane Horgan Lansdowne/Leinster 53
13- Brian O'Driscoll Captain Blackrock College/Leinster 72
12- Gordon D'Arcy Lansdowne/Leinster 29
11- Denis Hickie St.Mary's College/Leinster 56
10- Ronan O'Gara Cork Constitution/Munster 69
9- Peter Stringer Shannon/Munster 74
1- Simon Best Belfast Harlequins/Ulster 14
2- Rory Best Belfast Harlequins/Ulster 10
3- John Hayes Bruff/Munster 71
4- Donncha O'Callaghan Cork Constitution/Munster 33
5- Paul O'Connell Young Munster/Munster 42
6- Simon Easterby Llanelli 55
7- David Wallace Garryowen/Munster 35
8- Denis Leamy Cork Constitution/Munster 20
Replacements:
16- Jerry Flannery Shannon/Munster 12
17- Bryan Young Ballymena/Ulster 5
18- Mick O'Driscoll Cork Constitution/Munster 6
19- Neil Best Belfast Harlequins/Ulster 9
20- Eoin Reddan Wasps 1
21- Paddy Wallace Ballymena/Ulster 3
22- Andrew Trimble Ballymena/Ulster 13
