Sadio Mane’s second goal should have been disallowed for offside.
This, though, is one of the most difficult decisions for an assistant referee to get right, because when he takes a picture in his head at the moment the ball is played, it would appear to him the attacker is level and onside.
In this case, the assistant clearly did not realise Mane was coming back from an offside position.
Most of the training for officials is done with attackers making runs towards the opposition goal.
If assistants make mistakes, it is usually when attackers are offside but trying to get onside by moving away from goal, which happened in this case.
The Reds underlined their Premier League title credentials with a comprehensive 4-0 defeat of West Ham in their first game at Anfield.
