كتب : Hatem Maher
Mun In-guk’s 28th-minute goal from close range gave the hosts all three points.
Saudi Arabia's second successive defeat leaves them fourth in the five-team Group B with four points, three adrift of joint leaders South Korea and North Korea.
South Korea can move three points clear at the summit if they beat second-placed Iran later on Wednesday.
Winners and runners-up of the two groups qualify for the World Cup while third-placed teams meet each other and the winner enter a play-off against an Oceania side.