If we consider a striker in the squad with the equation that he must score goals, we are wrong. A striker not only scores goals but also tries to create goals with his team mates but also a striker makes an impact in a match which causes the team to do well. Many times it is seen that the opponent plans with only one main striker which gives the rest of the players a chance to do well in that match. When the opponent's target is only on one main striker, that main striker tries to score with other players instead of scoring, thereby allowing other players to score.
Haaland is an all-time regular for Manchester City and I don't think Pep Guardiola will ever consider Manchester City starting XI without him. When Haaland is included in the starting XI, the opposing manager will have extra plans for him which will give the rest of the players a chance to perform well in the match.
True, Halaand is not only tasked with scoring goals but creating spaces and assists. Pep knows his opponents very well, and when Halaand doesn't get a creative opportunity due to tight marking then the rest of the squad will do the job as they are evenly matched in squad depth.
The match against Newcastle in the second week will prove the depth of Man City squad, several key players are currently injured. This is the perfect time for a back-up to show similar qualities on Pep.