Rugby World Cup: O'Driscoll stunned by Ireland defeat to Japan

Ireland were sensationally upset by hosts Japan at the Rugby World Cup on Saturday, leaving Brian O'Driscoll stunned by their performance.

Rugby World Cup 2019: Devoid of ideas, devoid of energy - O'Driscoll stunned by Ireland defeat

Brian O'Driscoll believes Ireland have a huge amount of work to do if they are to challenge at the Rugby World Cup after a stunning defeat to Japan.

Joe Schmidt's Ireland came into the tournament as the world's top-ranked side and one of the favourites, starting strongly with victory over Scotland in their Pool A opener.

But from a 12-3 lead in their second match against Japan on Saturday, the Irish collapsed, failing to add another point as the inspired hosts claimed an incredible 19-12 triumph.

Ireland great O'Driscoll, appearing in his role as an ITV pundit, was keen to give the Brave Blossoms credit but saw huge issues with his country's display.

"The mood of the whole country has shifted in 80 minutes," he said. "I didn't see that happening.

"It was a tough game, playing against the host nation who had nothing to lose, but huge credit to Japan. They played terrific rugby.

"But Ireland looked very blunt. They looked devoid of ideas, they looked devoid of energy actually. I wondered if the conditions and the humidity took effect because it just wasn't the Ireland we've come to expect over the course of the last couple of years.

"It's very disappointing. It's not the end of the tournament - they can still top the pool - but they have some amount of work on if they're even thinking about getting beyond a quarter-final at this stage."

Paul O'Connell, another Ireland great working for ITV, added: "A big thing for Ireland over the last number of years has been their ruck.

"They've had the best ruck in the world in terms of their ball retention, in terms of their speed, and Japan have absolutely just done a job on them at the breakdown."