Eddie O'Sullivan believes France succumbed to the pressure of being World Cup hosts in last night's stunning 17-12 defeat to Argentina

But the Ireland coach fears Les Bleus' plight in the tournament curtain raiser does not bode well for his side when the Pool D rivals meet on September 21st.

The Six Nations champions woke up to a barrage of criticism from the French media this morning after Argentina registered a sensational victory.

Their hopes of reaching the quarter-finals now hinge on their match against Ireland with defeat sending them crashing out just two weeks into the World Cup.

A far kinder opener awaits Ireland against Namibia in Bordeaux tomorrow night, but O'Sullivan's belief that Pool D will remain a ferocious battleground has only grown after last night.

"The occasion got to France a wee bit in the opening 20 minutes and they forced the game and made a lot of mistakes," he said

"I suppose it's hard to believe that France will ever play that badly again in the World Cup. It was just one of those nights that didn't go for them.

"To be fair Argentina had a lot to do with that, but I think the sense of the occasion and the pressure got to France.

"Having the home crowd behind you can be a good thing but it can also bring a little bit of extra pressure to bear.

"It was a poor performance that they will be disappointed with and they will expect to fix it very quickly.

"We didn't discover anything from the game that we didn't already know - we always knew the pool was going to be tough and that looks even more the case now."

France enter their showdown in a fortnight knowing that only victory will be enough while Argentina, fuelled by grievances from their shoddy treatment by the international game, will now be convinced they can top the group.

But O'Sullivan is unwilling to gaze too far into the future, claiming the final standings of a group containing three of the world's top six sides could be determined by points difference.

"The result hasn't changed our plan. We started with the ambition off topping the group by winning all of our games," he said.

"The French bonus points could be important. You'd expect that in the games between ourselves, France and Argentina that all the games will be tight.

"In the worst case scenario if you didn't win those game you'd get a bonus point, without the opposition scoring four tries as well.

"That should balance itself out so there's a strong possibility the pool could be decided on points difference. But that's a way down the track — we have to get on with the job in hand.

"We can't get hung up on what happens in the other pool games. What happened in Paris last night can't detract from what we must do tomorrow, which is get a good result against Namibia.

"We need a big performance from the start. There will be a bit of nervousness of course because it's the first game of the tournament."

Ireland's chances of qualifying for the knockout stages will be improved if they amass a cricket score against the Namibians.

Namibia, who were spanked 105-13 by the Springboks last month, often offer dogged resistance before dropping off in the final quarter and O'Sullivan has warned against going for the jugular from the start.

"We've talked about not trying to win the game in the opening 20 minutes. We have to play ourselves into the game," he said.

"A good analogy is a cricketer going to the crease and trying to hit a six off the first ball. So it's about playing your way into the game, getting up to speed.

"It's our first match, it's going to be quite intense and there's going to be some nervousness.

"There's always a danger in rugby that if you try to do too much too soon you can lose your shape and then your confidence and that doesn't help you."  PA