Gary Neville believes the pressure is now on Ruben Amorim as Manchester United head coach and another defeat to Chelsea next week would create "big questions".
United suffered a 3-0 Manchester derby loss to rivals City to sit firmly in the bottom half of the table, with little evidence to show that the club can improve on last season's 15th-place finish.
Their four points from the opening four games means United have made their worst start to a Premier League season in 33 years.
Amorim's side have also exited the Carabao Cup after a humiliating second-round loss to League Two Grimsby Town on penalties, which means United are set for their shortest ever season in terms of games played.
Neville believes a loss to Chelsea next Saturday, live on Sky Sports , could be pivotal for Amorim's