Japan was held to a 0-0 draw by 10-man Greece on Thursday night in Natal, Brazil, leaving the Samurai Blue in a must-win situation going into its final Group C match in its drive to reach the knockout stage of the World Cup.
"We created many chances, but just couldn't turn them into a goal," coach Alberto Zaccheroni said in a TV interview.
Japan had the lion's share of possession, but failed to breach the Greek defence, while goalkeeper Eiji Kawashima turned away the few hot shots that came his way.
"The result is everything, it's disappointing we couldn't get the three points," Keisuke Honda said. "We had a problem with the precision of our play."
Japan finishes the group stage by facing leader Colombia on June 24 with nothing less than a victory needed to advance. Even then, the Samurai Blue's fate will also depend on the result of the other match between Cote d'Ivoire and Greece. A win by Cote d'Ivoire eliminates Japan, while a draw or win by Greece means the spot in the knockout round will be decided on goal difference.
Colombia defeated Cote d'Ivoire 2-1 in the earlier match Thursday to advance to the knockout round.
Japan, which lost to Cote d'Ivoire 2-1 in its opening match and would have been eliminated with a loss to Greece, is looking to advance out of the group stage for the second straight World Cup and third time in five appearances.
Zaccheroni made several changes to the lineup that lost to Cote d'Ivoire, most noticeably leaving midfielder Shinji Kagawa on the bench in favour of forward Yoshito Okubo.
Kagawa came on early in the second half as a substitute for striker Yuya Osako, with Shinji Okazaki moving to the top of the formation.
Japan had several scoring chances in the first half, with Osako putting an angled shot from just outside the area wide in the 20th minute and Honda having a free kick saved seven minutes later.
In the second half, substitute Yasuhito Endo, extending his record of caps for Japan to 146, assumed the free kick duty, but either was wide or had his shots parried by Greece keeper Orestis Karnezis.
In the 67th minute, Kagawa sent a long pass to Atsuto Uchida free deep on the right side of the goal. Uchida volleyed a pass across the front of the goal, but Okubo's shot on the far left went over the bar.
Greece's best chance to score came shortly after Japan gained the man advantage in the 39th minute, when midfielder Kostas Katsouranis was sent off after receiving a second yellow card.
Vasilis Torosidis rifled a shot from just inside the box that Kawashima stopped.
"It was a wasted opportunity," Okubo said. "It was shameful. I apologise to the Japanese fans."