Chelsea tasted defeat for the first time this season as Pep Guardiola's Manchester City ended a poor run against Thomas Tuchel's side to earn a deserved 1-0 victory in the Premier League at Stamford Bridge on Saturday.
Manchester United also slumped to a first Premier League defeat of the season as they went down 1-0 at home to Aston Villa -- paving the way for Liverpool to move clear at the top if they win at Brentford later.
West Ham United, who beat Manchester United in the League Cup in midweek, followed up with a 2-1 victory against Leeds United thanks to a late goal by Michail Antonio at Elland Road.
Norwich City's horrendous start to the season continued as they made it six defeats from six games with a 2-0 loss at Everton who joined Chelsea, Manchester United and Man City on 13 points.
Tuchel had enjoyed mastery over his Manchester City counterpart Pep Guardiola, winning all three matches against him since he took over at Stamford Bridge in January -- a sequence culminating in the Champions League final.
But this time Guardiola won the tactical battle as his side dominated possession and barely gave Chelsea, who were joint top before the lunchtime kickoff, a sniff.
Gabriel Jesus's neat finish on the turn in the 53rd minute earned City the win and they would have won by more had it not been for Chelsea goalkeeper Edouard Mendy.
The victory made Guardiola City's most successful manager with 221 victories since taking charge in 2016.
"I am so proud," Guardiola said. "What we have done in these five years -- players, backroom staff and all at the club -- working together to improve the club. It's an honour.
"Hopefully we can make more (wins) and the next manager can come and break the record. It means we have won many games. It's why we have won a lot of titles."
It was a reality check for Chelsea whose cautious approach backfired completely.
"We were excellent but only in the last 20 metres of the match, not in the other 80 metres," Tuchel said.
"Part of the performance is to make an opponent underperform and that is what City did today. They were stronger, sharper, had more precision."
Villa went ahead in the 88th minute at Old Trafford thanks to a header by Kortney Hause but the drama was only just beginning as United were then awarded a stoppage-time penalty after a handball by Hause.
Bruno Fernandes stepped up but blazed over, with manager Ole Gunnar Solskjaer unhappy that Villa's players had tried to put off the Portuguese as he prepared to take the kick.
"Bruno has been such a good penalty taker," Solskjaer told reporters. "You would back him with your mortgage. What I did not like to see was the way they crowded the penalty spot and the referee to try to affect Bruno.
"It clearly worked for them but that is not great to see. They achieved what they wanted to."
Leeds looked to heading for a first league win of the season after Raphinha's low finish in the 19th minute.
But in a fast and furious game West Ham levelled when Jarrod Bowen's shot deflected in off Junior Firpo in the 67th minute.
Antonio then sealed it in the 90th minute to move the Hammers into seventh spot with 11 points.
Jamie Vardy scored twice for Leicester City and once for Burnley in a 2-2 draw, although Burnley had a late 'winner' cancelled out by a VAR check.
Watford also had a late goal disallowed by VAR as they came back to draw 1-1 at home to Newcastle United.