Bernard Laporte's men must win at Lansdowne Road if they are to stay in the title hunt but doubts linger over which French team will turn up.

The defending Grand Slam champions were below-par against Scotland and England but won, while they dazzled for long spells against Wales only to taste defeat.

O'Sullivan insists, however, that no matter what Les Bleus side materialises, Ireland can expect to come under tremendous early pressure.

He said: France will go for us in the first half and it would be stupid to expect anything else. They will come out and give it a real go. How we cope with that will be a big test.''

Wales were on the back foot for most of the first half of their dramatic clash in Paris but fought back after the interval to claim a heroic 24-18 victory.

O'Sullivan was full of praise for the Welsh performance but felt France contributed to their own downfall - a mistake he does not expect to see repeated on Saturday.

Wales were outstanding in the first half when they had their backs to the wall for the whole 40 minutes. They could have been 29 points behind at half-time, not nine,'' he said.

It shows what can happen if you are resilient and manage to hold out. They fought back at the right time and it paid off.

But France are an intelligent side and they will not make the same mistakes again. They are expected to do better this time.

We have to expect the French side which turned up for the first half against Wales and forget about the second half.