Sean O'Brien has insisted that there is still more to come from Ireland following their resounding victory over Canada.

The Six Nations champions showed their Rugby World Cup credentials by seeing off the Canucks 50-7 in their opening game at the Millennium Stadium.

Despite the comfortable win, O'Brien says that Ireland will look to learn lessons from their performance ahead of their next Pool D meeting with Romania in eight days' time.

"It is always important to put in a big performance," he told Sports Mole. "But we will go back and assess things on Monday and see what we didn't do.

"I think we actually probably left a few scores out there. We have also got to make sure that we don't let teams into games."

Ireland were backed by a vocal following in South Wales, with many thousands making the short trip across the Channel, which O'Brien was delighted to see.

"The crowd were brilliant today," he added. "When we were coming into the stadium they were doing what Irish people do - going nuts!"

Ireland follow up their meeting with Romania by taking on Italy and France in the coming weeks.