Six Nations

France retained their crown on points difference alone with a dubious late try from Elvis Vermeulen, awarded by the television match official, edging them past Ireland.

O'Sullivan believes the decision to allow the try was an example of Ireland's lack of fortune during the championship.

"We thought we had won the Six Nations until the final seconds in Paris. It was a tough, emotional tournament," said the Ireland coach.

"I've always said the Six Nations is a tough competition to win. You need to play well and be lucky with injuries, which overall we were as we kept a pretty healthy profile.

"But you also need the rub of the green at some point in the tournament. People say you make your own luck but we could say hand on heart that luck wasn't on our side on Saturday.

"We didn't get a lot of luck in the Six Nations so I hope we get some in the World Cup."

Ireland put themselves in a magnificent position to clinch the title with a spellbinding 51-24 victory at the Stadio Flaminio that saw Italy cut to ribbons.

And while Irish title hopes were ultimately dashed by the narrowest of margins, O'Sullivan feels the display in Rome will stand the team in good stead for the summer tour to Argentina and World Cup.

"Our performance sent a message out because our accuracy was right up there. We did create a lot of chances and took them," he said.

"In the first half we managed to get three tries without having the best possession.

"There was a lot of good in that and we have to take a step back and say that it was a good performance against Italy.

"They were on a high after taking two big scalps but we put them to the sword in a pretty clinical way. That's got to carry some weight.

"Now have to keep that momentum and kick on."

Ireland have finished Six Nations runners-up for five of the last seven championships but O'Sullivan is pleased by the consistency, especially in light of how quickly the landscape can change.

"I'd prefer to come first but I'd rather be second than third. This championship can go different ways," he said.

"Wales won a Grand Slam two years ago, and deservedly so, but on Saturday faced a dogfight with England not to get the wooden spoon. It's a slippery slope.

"Of course I'm disappointed but you do your best and that's it. You have to be philosophical, especially when things become out of your control.

"Once we'd lost to France we knew this scenario was in the offing and all we could do was keep going out and winning.

"That's what we did but it wasn't enough to take the title."