All Blacks legend Dan Carter has revealed that the side's loss to France in the 2007 Rugby World Cup quarter-final was a result of insufficient mental preparation.

Speaking to the Guardian before his move from Europe to Japan next month, Carter says that if he could to do it all again he would focus on his mentality.

"If I could change one thing in my career I would pay more attention to the mental side from the start," Carter told the Guardian.

"The defeat to France was a huge lesson. Under pressure, we withdrew into ourselves and stuck to what the coaches had said.

"We stopped thinking. I learned then that for all the time you spent in the gym and on the training field, not enough was done in terms of mental preparation."

Carter burst onto the provincial rugby scene in 2002 before making his Super Rugby debut in 2003, he would make his All Blacks debut in the same year.

The leading points scorer for international rugby was haunted from the 2003, 2007 and 2011 World Cups having been apart of all campaigns.

The eventual 2015 World Cup champion revealed that not enough emphasis was put on his mental status.

"When I started my career, if you said you were going to see a psychologist, everyone would ask if you were all right. Now they say that if you don't.

"It allowed me to confront my demons so that playing France in another quarter‑final in Cardiff became a positive, lucky enough to have the chance for revenge, rather than being haunted by ghosts.

"It is amazing how powerful a tool the mind is," he told the Guardian.

Carter, 36, is moving to Japan next month having signed with the Kobelco Steelers for a two-year contract.

Today he joins Usain Bolt, Gordan Ramsay and Kevin Pietersen in the World XI for the 2018 Soccer Aid match at Old Trafford.