"But we'll be alright if we win at home. We have sufficient time.

"It was very unfortunate but we still have plenty of chances ahead to qualify."

Ala'a Hubail, Bahrain forward, headed home in the 74th minute as Japanese goalkeeper Yoshikatsu Kawaguchi could only parry a cross from the left by Ismail Abdullateef.

Japan had not lost a match, winning three and drawing three, since Okada took over from Ivica Osim after the Bosnian suffered a serious stroke in November.

However there have been mixed reviews for Okada, who guided Japan to their winless World Cup debut in 1998, as he now leads their bid for a fourth straight appearance on the world stage.

Lagging behind

"Where has Japanese football gone?" Japan daily Asahi Shimbun lamented, saying Japan had let go of their "crisp short passes, unpredictable combination plays and well-timed individual skills."

Okada's Japan have "destroyed the meticulous football built by Osim," the paper added.

"It was a total loss although the score was 1-0."

Japan did not have their strongest team however, with Celtic dead-ball specialist Shunsuke Nakamura tied up with club commitments, Eintracht Frankfurt defensive midfielder Junichi Inamoto out through injury, and former Frankfurt striker Naohiro Takahara sidelined after twisting his right thigh in training.

Okada's players admitted they lacked the determination to overwhelm the physically stronger Gulf side.

"We did not run as hard as our opponents did today. It is especially important when you play away," said Yasuhito Endo, Gamba Osaka midfielder.

"We lagged behind in every aspect."

Yuki Abe of Urawa Reds added: "We were short on our work rate overall.

"Our opponents went full out and fell down to the pitch. They were different. We had to give out more."

Each side will play four more matches in June with the top two countries in each group advancing to the final Asian qualifying round.