Bournemouth can count themselves rather unfortunate not to leave Anfield with a point since Christian Benteke's winner should have been disallowed, following the changes to the offside rule.
In essence, the change to the rule is a simple one and is centered on when a player is adjudged to be interfering with play.
Law 11 of the official football rules deal with what referees and their assistants must take into consideration when deciding whether a player is 'interfering with an opponent' or 'gaining an advantage'.
Under the old rules, interfering an opponent meant: preventing an opponent from playing or being able to play the ball by clearly obstructing the opponent's line of vision or movement or making a gesture or movement which, in the opinion of the referee, deceives or distracts an opponent.
Under the new rules, interfering with an opponent means: means preventing an opponent from playing or being able to play the ball by clearly obstructing the opponent's line of vision or movement or challenging an opponent for the ball.
Under the old rules, gaining an advantage meant: playing a ball that rebounds to him off a goal post or the crossbar having been in an offside position or playing a ball that rebounds to him off an opponent having been in an offside position.
Under the new rules, gaining an advantage means: playing a ball that rebounds or is deflected to him off the goal post, crossbar or an opponent having been in an offside position; Or that rebounds, is deflected or is played to him from a deliberate save by an opponent having been in an offside position; Or, a player in an offside position receiving the ball from an opponent, who deliberately plays the ball (except from a deliberate save), is not considered to have gained an advantage.
Now look at the Liverpool goal against Bournemouth:
As the cross comes in from the left flank, Philippe Coutinho was in an offside position and clearly makes a play for the ball before it arrives at Benteke, who then puts it into the back of the net.
Whether or not Coutinho made contact with the ball is irrelevant. Coutinho challenged for the ball from an offside position, which should have resulted in the referee blowing his whistle and awarding a free-kick to Bournemouth even before the ball arrived at Benteke.