Ireland's Grand Slam ambitions were brought to a heart-rending conclusion when they surrendered a winning position seven minutes into injury time in a dramatic 20-17 victory for France.

The record 43-13 destruction of England at Croke Park on Saturday revived flagging Irish spirits and also nudged their Six Nations title bid back on track.

But head coach O'Sullivan knows that should Scotland and Italy be dispatched as expected, Ireland will begin mourning for the one blot on their championship record.

'If France gave us a good hiding or won by 10 or 15 points it would be easier to take,' he said.

'But the hard thing to take about the result is that we put ourselves in a winning position.

'We all thought when Ronan O'Gara kicked his last penalty it was job done. The loss was the cruellest of blows and we've never suffered one like it before.

'England lost four possible Grand Slams under Sir Clive Woodward. They had four cracks at it before winning, which indicates how difficult it is to do.

'England had to live with that and they got better because of it - that's the approach we must take.

'But if we go on top and win the next two matches then that France game will always be on the back of our minds.'

Unbeaten France are in the driving seat to retain their RBS 6 Nations title with fixtures against England at Twickenham and Scotland in Paris yet to come.

O'Sullivan has not given up hope of one of them halting the French juggernaut and is hoping he will need his calculator with the championship then likely to be decided by points difference.

'We can still win four out of five. France didn't win the Grand Slam last year because they lost to Scotland, but they still won the championship,' he said.

'England have France at Twickenham and they believe they can win that game.

'If that happens it will open the championship up once again and it will come down to points difference. That's about as good as we can do at the moment.'