Alberto Zaccheroni's team have won three of their first four matches, scoring 11 goals and conceding only one, which came in a draw against Australia, their only dropped points so far.
Oman were beaten 3-0 in Saitama in the opening round of fixtures but are handily placed in third following their 2-1 win over Jordan last month, and Zaccheroni has warned his players they cannot afford to slacken their pace.
He told the Japan Football Association website: "The game at Oman will be important for us. We are going to have three away matches in the latter half of the qualifiers and it will be down to how many points we can collect in those away games.
"Oman work well as a unit and have good composure. They played defensively at Saitama but usually they come out to attack. We'll have to concentrate against Oman."
Japan will be without their playmaker, Manchester United's Shinji Kagawa, who has been ruled out by a knee injury, while Oman's talisman, Wigan goalkeeper Ali Al Habsi was a doubt but has been passed fit.
Assistant coach Muhanna Said al Adawi said of the clash in the Oman Daily Observer: "It will be a difficult match. We all respect Japan and will do our best to get a positive result."
The other match in Group B sees Iraq host Jordan. The hosts are looking for their first win while Jordan go into the game only a point behind Oman.
In Group A, second-placed Iran will hope to capitalise on Korea Republic's inactivity to go top when they meet third-placed Uzbekistan in Tehran while bottom two sides Qatar and Lebanon meet in Doha.
Wednesday's 2014 FIFA World Cup Qualifying (AFC) Fixtures
Qatar vs Lebanon
Iran vs Uzbekistan
Oman vs Japan
Iraq vs Jordan