Rob Kearney is "more than happy" to chase peak match sharpness and start Ireland's World Cup clash against Romania at Wembley Stadium on Sunday.

Full-back Kearney expects head coach Joe Schmidt to make changes to keep his squad fresh ahead of facing the world's 17th-ranked side in London.

However, Leinster stalwart Kearney could well be handed a second straight run-out following last weekend's 50-7 victory over Canada with the 29-year-old aiming to hit top gear after a knee niggle.

Ireland declared a "clean bill of health" on Sunday, aside from Robbie Henshaw, but even the Connacht centre is expected to recover from hamstring trouble in time to contest selection for the Romania clash.

"I haven't seen the full medical report yet but there will be a few guys who maybe won't be fit for this weekend, or might be rested based on a couple of niggles," said Kearney.

"So it's not like the Six Nations or November when you have an unlimited number of people to choose from.

"So some people will be asked to double up again, and when you're asked to double up at a World Cup, you're more than happy."

Ireland shook off two consecutive defeats that closed their warm-up schedule by blasting seven tries past Canada in Saturday's Pool D opener in Cardiff.

After Romania this weekend come the group defining battles against Italy and France, with Kearney confident Ireland are edging towards their attacking best.

Schmidt's side were labelled conservative en route to their second straight Six Nations title this season, but Kearney insists expansive play will be reined right in by every side as the tournament progresses.

Kearney admitted the heat under Cardiff's closed roof and the breathless pace against Canada sapped Ireland's strength.

"Yeah, I was tired. I haven't been that spent now in a long, long time," said Kearney of the Canada victory.

"I don't know if it was the first proper competitive game back, the roof closed, or the fact there was a huge amount of ball in play.

"I've pulled up okay but I was unbelievably tired after the game.

"I was asking around the lads after the game hoping they'd say the same so I wasn't miles off the pace.

"But the general consensus was that the pace was very, very quick.

"It was great to score some tries after the criticism in the Six Nations that we weren't creating enough.

"The criticism didn't hurt, because ideally you want to be scoring tries but what matters is winning games.

"As this tournament goes on and teams get more evenly matched and the margins are smaller, you'll see a lot more aerial contesting and kicking of ball.

"That's a tactic teams will use when the stakes are higher."

Wing Dave Kearney has fought his way back into Ireland's starting line-up after injury trouble, leaving older brother Rob proud of their World Cup family ties.

"I'm really happy to see him get what he deserves - maybe I'm a little biased but he was always very much part of the team in my mind," said Rob Kearney.

"Had it not been for injury he may well have featured in the Six Nations.

"He needed to take his opportunities, but he has and it's been great to see."