The defeat marks the first time City coach Pep Guardiola has lost four in a row in his managerial career.
Haaland has now scored 67 Premier League goals since joining City in the summer of 2022.
Four minutes before the end of normal time, Leandro Trossard sealed the win for Arsenal from a launching pass by Havertz.
Arsenal dropped from top of the Premier League table to second place after the Gunners played out a goalless draw against Manchester City at the Etihad Stadium on Sunday
Barely four minutes later, Levi Colwill doubled the lead for Chelsea.
United have several injury issues to deal with and have confirmed Sergio Reguilon will be absent against Crystal Palace on Saturday.
Jonny Evans, who was making his first United start after eight and half years, provided Fernandez with the assist for the goal from the middle of the pitch.
With his brilliant performance and contributions last season, Saka, 21, clinched this year’s edition of the award after three previous nominations.
“Chelsea is delighted to announce the signing of Ecuador international Moises Caicedo,” the Blues said in a statement on Monday.
Brighton took control of the game from Chelsea in the second half, grabbing a win and ensuring Chelsea remained 11th on the table.
