Kevin De Bruyne shredded Watford with a playmaking masterclass, so Pep Guardiola scratches his head when the Belgian makes a simple mistake.
Liverpool's record-breaking start to the season continued at Chelsea after Manchester City steamrolled Watford.
Bernardo Silva said his tweet to team-mate Benjamin Mendy was a "joke" but the Football Association is to investigate his post.
After losing 2-1 to Liverpool at Stamford Bridge, Frank Lampard said his Chelsea side should aim to reach the Reds' level.
Jurgen Klopp explained how Sadio Mane suffered two injury issues in Liverpool's 2-1 win over Chelsea at Stamford Bridge on Sunday.
Jose Mourinho was critical of Manchester United's loss at West Ham, but Ole Gunnar Solskjaer did not bite back at his predecessor.
Manchester United's problems on the road continued with a 2-0 defeat at West Ham, while leaders Liverpool made it six wins out of six.
Half of the Premier League's 'big six' all lost at the weekend, with Liverpool and Manchester City showing they are way ahead of the rest.
Liverpool survived a late fightback to earn a 2-1 win at Chelsea, after which Jurgen Klopp admitted Manchester City make winning look easy.
Ainsley Maitland-Niles was sent off for Arsenal but late goals from Calum Chambers and Pierre-Emerick Aubameyang gave them all three points.