Bulgaria continued their unbeaten run in 2013 and gave themselves a boost ahead of the second half of their World Cup qualifying campaign with a comfortable win in Japan in their international friendly.
The eastern European side currently lie second in in their group - three points behind Italy - and are unbeaten from six matches as they bid to qualify for Brazil 2014.
However, they were grateful for two defensive errors from Japan, who top their Asian qualifying group by six points, with Stanislav Manolev's 25-yard free-kick setting Bulgaria on their way to victory in the opening minutes.
There looked to be no danger when the PSV Eindhoven defender fired at goal and while the ball did dip slightly, Japan goalkeeper Eiji Kawashima will have been disappointed he could only palm the ball into his own net.
Takashi Inui thought he had levelled for the hosts midway through the first half but the effort was chalked off for offside, while Manchester United playmaker Shinji Kagawa saw his turn and shot palmed away.
Japan's failure to take their chances came back to haunt them in the 71st minute when Makoto Hasebe could only direct Hristo Zlatinski's free-kick into his own net.