Rugby World Cup Ireland v Argentina: Johnny Sexton can help cope with void left by Paul O'Connell exit
It was terrible to see Paul O'Connell's Test career end the way it did last weekend but Ireland can cope with his loss against Argentina on Sunday as long as Johnny Sexton is fit to take part.
As a leader, it's impossible to fill the boots of the great captain.
He's a man who doesn't just talk the talk, he walks the walk too and he's been instrumental in everything that Ireland have done over the last number of years.
Peter O'Mahony and Sean O'Brien are big losses too, for the first hour of the France game you couldn't have picked between the two for man-of-the-match, but I just think that it's his out-half Schmidt knows he can't do without.
The likes of Iain Henderson and Chris Henry are going to come into the team, and they're capable of doing a fantastic job, but I don't see the same depth at number 10.
Ian Madigan performed well off the bench last week but does he have the astuteness needed against a team like Argentina?
I'm not sure.
I enjoyed watching him play against France, and you have to say he did well in a tough situation, but you didn't know whether he was going to create a try or give up an intercept.
Ireland need to keep this game structured, something Sexton does so well, but Madigan is more the type to say 'let's go for it.'
That wouldn't be playing to our strengths this weekend.
Argentina play the type of rugby that I always like to coach.
Their general movement, their awareness and their footwork have all been second to none in this tournament and they're the team that has impressed me most.
It's a game almost too close to call.
People seem to be looking past it to a certain extent, the euphoria of avoiding the All Blacks I suppose, but this will be Ireland's hardest test of the last three years.
Even playing the likes of New Zealand in November internationals won't compare given what's at stake for the winners.
France were poor in Cardiff, another sad reflection of the depths to which their game has fallen, but Argentina are a different proposition altogether.
Add their fine form to the weight of expectation that Ireland are going to be under and you could easily foresee a slip up.
The pressure is really on to reach a first semi-final now and that's the only way this tournament will be viewed as a success.
It didn't take a medical degree to realise that O'Connell and O'Mahony would play no further part in the tournament during the game last week and Ireland harnessed that emotion well.
They'll be out to do it for their missing team mates again but can they do it two weeks in a row?
That's the important question and the leaders, the likes of Jamie Heaslip, Rory Best and Rob Kearney, are really going to have to step up.
If not, I worry that we could be writing another chapter in Ireland's big book of quarter-final failures.
Ireland v Argentina is the pick of the ties on this weekend and I think it's hard to look past the southern hemisphere sides in the other three games.
South Africa have a real look about them now and they're gaining momentum. They've put the Japan game behind them, and Wales will be physical, but the Springboks could go all the way.
France have been terrible but the performance of New Zealand will be important as well as the result.
They need to gain some momentum for the challenges ahead after not hitting top gear and it's hard to see Australia slipping up against Scotland given how they've been going.
Looks like it will be up to Ireland to represent the northern hemisphere!
The tournament keeps getting better and better but the disciplinary process has struck a bit of a sour note this week.
It's been inconsistent, there's no way around that. World Rugby have clearly targeted two things, the neck roll and the tip tackle, but it's tough to see Jonny Gray and Ross Ford miss out on one of the biggest games of their career for Scotland.
There's people complaining about the O'Brien ban but if Nigel Owens had saw it at the time then it was a borderline call.
If he had went yellow instead of red then the big flanker would be available to play this week!