Billy Vunipola has joined Owen Farrell in being banned for the start of the World Cup after receiving a three-week suspension for his red card against Ireland.Vunipola was sent to the sin-bin for a dangerous tackle on Andrew Porter in Saturday's 29-10 defeat at the Aviva Stadium, but the offence was upgraded to a red by the bunker review system.An independent disciplinary hearing reduced the entry-level ban of six games to three because of mitigating factors and the Saracens number eight could shave an additional match off the total if he attends tackle school.It means he will miss Saturday's final warm-up fixture against Fiji at Twickenham and the pivotal World Cup opener against Argentina on September 9.The decision comes the morning after Farrell was given a four-match ban for his dangerous tackle on Wales flanker Taine Basham on 12 August and is another grave setback for Steve Borthwick.England's head coach must now plan for the opener against Argentina without his captain and talisman as well as the only specialist number eight in the squad.Vunipola will be available for the clash with Japan in Nice on 17 September when he completes tackle school but Farrell will not be back until the final group games against Chile and Samoa.