Kobe - Ireland captain Rory Best admitted his side's confidence was shaken by their shock loss to Japan, but said they were happy to remain in control of their own destiny heading into their last World Cup pool game.

The injury-hit Irish followed up that stunning 19-12 defeat by the hosts with an unconvincing 35-0 bonus-point win over lowly Russia in Kobe on Thursday.

Yet after starting their Pool A campaign with a 27-3 victory over old rivals Scotland, Ireland know a win in their final game against Samoa will earn them a last-eight clash, probably against reigning world champions New Zealand or South Africa.

"You want to get into the last round with your destiny in your own hands," veteran hooker Best told reporters on Friday.

"We're there. We would have expected to be in a better place after three games, to have won the three games, but that hasn't happened," added the 37-year-old, who will retire after the World Cup.

"We're here to play in the quarter-finals. We've made no secret of that."

Best was adamant the squad's self-belief remained intact despite the Japan defeat -- a result that left Ireland needing to make history if they are to be crowned world champions for the first time.

No team has ever lifted the Webb Ellis Cup after losing a pool match along the way.

"I think when you lose a game and go from being supposedly contenders in the first game to useless in the second game, it's always going to affect the confidence a little bit," said Best.

Best urged the team to return to basics, acknowledging that Ireland lost the ball too much against Japan, were not as effective as usual at the breakdown and were weaker than expected in their pressure and territory game.

"When we were 12-3 up, we had a few opportunities and we turned the ball over cheaply, gave away penalties.

"With Japan, we allowed ourselves to make a couple of mistakes before we then tried to fight back, or we had one good moment and didn't back it up with another good moment," said Best.

Ulster front row Best did not play against Russia, with Ireland coach Joe Schmidt making 11 changes to his side. Their final pool game against Samoa is on October 12.

"It was important to get five points last night and now it's important that we take a couple of days just to regenerate, to refresh everyone a little bit," said Best.

"It's very, very rare in a World Cup where you get a weekend where you have no game and you get a longer turnaround like we have now."