By Alastair Himmer

TOKYO (Reuters) - The logic behind Japan coach Takeshi Okada's bombshell that he had targeted a semi-final spot at the World Cup is hard to fathom.

His refusal to backtrack after the Blue Samurai were drawn alongside the Netherlands, Cameroon and Denmark at the tournament in South Africa has tightened the squeeze on his players.

Breaking party ranks, Japan captain Yuji Nakazawa told Reuters the three-times Asian champions would be on an early flight home if they lost their Group E opener to Cameroon.

His international team mates appear petrified of mentioning the dreaded the "S"-word since Okada declared he would settle for nothing less than a best-four finish.

All the evidence points to Japan making another quick exit after slumping to third in the East Asian championships in Tokyo and a 3-0 home drubbing by Serbia in the World Cup run-in.

Japan Football Association (JFA) president Motoaki Inukai refused to shake Okada's hand after the Japanese were beaten 3-1 by fierce rivals South Korea at the East Asian tournament.

Inukai said Okada "might stay on if he achieves his target" -- which most took to mean the JFA were on the lookout for a new coach -- but Okada has no plans to carry on after the World Cup.

Japan have failed to make any concrete progress since flattering to deceive under Philippe Troussier at the 2002 World Cup.

Zico's failure to get the best from the so-called "golden quartet" of Hidetoshi Nakata, Shunsuke Nakamura, Junichi Inamoto and Shinji Ono slammed the brakes on the team's development.

Former coach Ivica Osim suffered a stroke months after his side fell to Australia at the 2007 Asian Cup and Okada has failed to deliver in his second spell in charge.

Okada's semi-final goal was a bolt from the blue and it is difficult to see where Japan will pick up the points required to advance from their first-round group in South Africa.

Inamoto could be used as a shield for the back four in Japan's opening game on June 14 against a powerful Cameroon side led by the prolific Samuel Eto'o.

How Japan go about piercing the amour of Cameroon and the Netherlands, in particular, is another matter and Okada will need a struggling Nakamura to rediscover his best form quickly.

Europe-based midfielders Keisuke Honda, Makoto Hasebe and Daisuke Matsui represent Japan's biggest threats but Okada's side are likely to find points very hard to come by once more.

(Editing by Miles Evans)