Japan lost back-to-back games for the first time under Alberto Zaccheroni as the Asian champion was beaten 2-0 by Bulgaria in a World Cup qualifying tuneup on Thursday evening.
Bulgaria produced a solid display to win, behind an early Stanislav Manolev free kick and a second-half own goal by Japan captain Makoto Hasebe.
Japan, which was coming off a shock 2-1 away defeat at the hands of Jordan in March, hosts Australia on Tuesday at Saitama. A draw would make it the world's first team to qualify for the 2014 World Cup in Brazil.