Ireland captain Paul O'Connell is a major doubt for the Rugby World Cup quarter-final clash with Argentina with an upper hamstring problem which forced the 35-year-old off during the win over France in what could potentially be his final international appearance. O'Connell will be assessed this week along with Johnny Sexton and Peter O'Mahony, who were also substituted, however coach Joe Schmidt is optimistic over the fitness over the duo.

Sexton has suffered a suspected adductor problem which saw him withdrawn in the first half, while O'Connell was stretchered off at the break after collapsing to the floor. O'Mahony fell awkwardly after falling backwards in a tackle and leaves the Irish facing the last eight clash without three key players.

But Schmidt is hopeful both Sexton and O'Mahony will be available but admits O'Connell's injury is the one which concerns him the most. Speaking after the 24-9 win at the Millennium Stadium, he said: "The challenge grew in complication with the loss of Johnny Sexton, Paul O'Connell just before half time and Peter O'Mahony. I think that is 200 plus caps and it does make it a challenge. It was battle that showed a fair bit of character in the side.

"The update I can give you is it doesn't look great with Paul," the New Zealand born coach added. "It looks like an upper hamstring but we're going to wait until tomorrow to get that scanned to make sure the information has decreased a little bit. Johnny, it looked like an adductor to me but it is not the learned eye of a medic so we are probably going to get Johnny scanned tomorrow with Peter O'Mahony.

"Peter actually didn't seem too bad so we're hopeful. I think it is a twist of the ankle or the knee. He was walking pretty well in the changing room and hopeful we he is going to be be ok. I don't know if it is the ankle or the knee as I haven't had the chance to get in there and talk to him. I have spoken briefly to Johnny and he is already talking about next week. I'm not sure if that means he is going to be playing or not. It is probably Paul who worries me the most of those three."

Flanker Sean O'Brien could also be unavailable as he faces an anxious wait to discover whether he will be cited for striking France lock Pascal Pape during the first 40 minutes, but Schmidt has launched an impassioned defence of the Leinster blindside. "I truly hope [he is] not [banned]," he stated.

"He was being held at the time and I don't think he is looking directly at the player but it not for me to determine. It also think is not a closed fist. I'd be hopeful but it is not a decicion for me and I hope it is not something that impacts on us. Considering the dressing at the moment with the amount of injuries we have we can ill-afford to lose another player particular one of Sean's experience and standing in the group."

Meanwhile, France coach Philippe Saint Andre remains upbeat despite seeing his side overwhelmed by Ireland and forced into a last eight meeting with New Zealand, which sparks memories of Les Blues' two Rugby World Cup victories over the All Blacks in 1999 and 2007. Saint Andre will leave the post after the tournament and says his side must rouse themselves again for the quarter-final.

"We need to recuperate and analyse and while keeping mind that we are till in the tournament," he said. "We need to recover for a big game in Cardiff against the All Blacks. In the first half we were behind but we are still in the match. In the second half even though it is possible to come but after the 60th minute we were dominated. We are also in difficulties we couldn't have clean ball and that mean it becomes complicated when you're always defending.

"It was a very intense match but we don't have many injuries, the Irish have two or three very serious injuries while on our side that is not that many. What is working is we made far too many mistakes in the offence and we also took a lot of penalties but we are still in the race. We are not out of the race but we need to regroup and prepare for a huge fight against the All Blacks."