Maya Yoshida played the full 90 minutes as Japan made it two wins from two in Group F of the AFC Asia Cup with a 1-0 win against Oman.
Hajime Moriyasu called upon his side to show the same intensity as their second-half performance against Turkmenistan, where they came from 1-0 behind to win 3-2, and it took Samurai Blue just 28 minutes to break the deadlock.
Genki Haraguchi was brought down inside the area before stepping up and sending his penalty past Faiz Al-Rushaidi.
Japan now face Uzbekistan in their final group game on Thursday 17th January in a 1.30pm GMT kick-off before the knockout rounds.