Saudi Arabia's quest for a fourth successive International Federation for Athletes with Intellectual Impairments (INAS) Football World Championships title in Kil in Sweden took shape with a tough victory over Japan.
The Gulf powerhouse were given a stern examination at the Sannerudsvallen stadium.
But a goal from Abdullah Al-Dosari in the 74th minute proved key as they maintained their unbeaten Group B record.
European champions Poland are also unbeaten at the top of the group.
France also won 4-0 over Germany at the Örsholmens IP in Karlstad in Group A.
Argentina continued their unbeaten record by default elsewhere in the group after a 3-0 win over absent South Africa, a late withdrawal from the event.
The event is taking place in stadiums in four towns across Sweden: Tingvalla IP and Örsholmens IP in Karlstad, Sannavallen in Kristinehamn, Solviksvallen in Arvika and the Sannerudsvallen in Kil.
Saudi Arabia are due to face Poland tomorrow in a battle between the Group B heavyweights in Kristinehamn, while Russia will play Japan in Karlstad.