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Cristiano Ronaldo failed to score for the first time since returning to Manchester United
Liverpool ended the weekend on top of the Premier League but Manchester City were the big winners as they were the only one of the top four to win.
City got revenge on Chelsea for losing last season's Champions League final by reversing the score from Porto in a 1-0 win at Stamford Bridge.
Manchester United's 1-0 home defeat to Aston Villa and Liverpool's 3-3 draw at Brentford rounded off a perfect day for Pep Guardiola's men.
All four sides are now separated by just one point after six games, but Brighton could go top if they win at Crystal Palace on Monday.
AFP Sport looks at three talking points from the weekend:
Chelsea's Champions League success completed a hat-trick of wins over City towards the end of last season in three different competitions.
Had the Blues emerged victorious once more, Thomas Tuchel would have become the first coach to ever beat Pep Guardiola in four consecutive matches.
Instead, Guardiola turned the tide on the German as a City masterclass starved Chelsea of possession and strangled them with an intense press when they did have it.
Tuchel agreed his side has played well in the 20 metres in front of their own goal because they couldn't get any further up the field.
Even victory at a title rival could not silence the questions over why City did not splash out for a recognised striker in the transfer window as a 1-0 win was scant reward for their dominance.
But they did enough to lay down a marker, as they have in the past at Stamford Bridge in title-winning campaigns under Guardiola.
Victory almost four years ago to the day signalled a changing of the guard from one champion to the next and last season's 3-1 win to start 2021 came towards the beginning of a 21-game winning run that blew away any other contenders to the title.
Cristiano Ronaldo's return raised expectations United could take the title back across Manchester for the first time since Alex Ferguson left as manager in 2013.
However, when Ronaldo was running riot for Ferguson's teams in his first spell at United, the Portuguese was a difference maker in a balanced team of proven winners.
Now he is the biggest but just the latest star in an expensively assembled squad lacking in cohesion.
United have now lost three of their last four games to again put Ole Gunnar Solskjaer's position as manager under scrutiny.
Solskjaer made the brave call to keep Bruno Fernandes on penalty duty over Ronaldo.
Fernandes had scored 21 of his 22 United penalties, but with his more esteemed international colleague watching on, blazed a stoppage time spot-kick into the Stretford End.
Just three weeks ago, Arsenal were off to their worst league start in 67 years with Mikel Arteta's future as manager called into question with his side bottom of the table.
Three consecutive wins later, the Gunners are back in the top half and back on top in north London after blowing Tottenham away with three first-half goals in a 3-1 win at a delirious Emirates.
A £150 million ($205 million) summer spend on six players aged between 21 and 23 is already starting to bear fruit with Aaron Ramsdale, Ben White, Takehiro Tomiyasu, Martin Odegaard, Albert Sambi Lokonga and Nuno Tavares all playing their part.
But it was another two young stars developed by the Arsenal academy that offer most hope for the future.
Emile Smith Rowe and Bukayo Saka tore Tottenham apart before the break to grab a goal and assist each.
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