Asian heavyweight Japan took a huge step toward qualifying for the Qatar 2022 FIFA World Cup after beating Saudi Arabia 2-0 in Saitama Tuesday.

Liverpool forward Takumi Minamino gave the four-time Asian champions the lead midway through the first half, before Junya Ito bagged another shortly after the break.

The Saudis went into the game four points clear of Japan at the top of Group B, knowing that a win would seal their place in Qatar.

But Japan's victory instead set up a tense battle for the two automatic qualifying spots with two games remaining, with Australia also still in the hunt.

Japan started the qualifying campaign with two losses from its first three games but has now won five in a row.

Again shrugging off the absence of key defensive pair Maya Yoshida and Takehiro Tomiyasu, the home side started strongly and took the lead in the 31st minute.

Ito burst clear of a Saudi defender down the right to square a low cross that Yuya Osako left for Minamino, and the Liverpool man's shot looped up off the goalkeeper and in.

Ito then got himself on the scoresheet – his fourth goal in four games – slamming the ball home from the edge of the area in the 50th minute.

Japan is away to Australia in its next match and finish the campaign at home to bottom side Vietnam.

The Saudis travel to China before facing Australia at home.