Manchester City's unbeaten Premier League start ended at Villa Park on Saturday, and the post-mortem has two obvious culprits.
Jackson punishes Guehi's early gift
Aston Villa made the faster start and were rewarded inside six minutes. Marc Guehi's poor first touch in a dangerous area handed possession to Nicolas Jackson, who needed no second invitation to open the scoring.
It was the kind of error that has become a worrying theme. Guehi was at fault for both of Ipswich Town's goals in a previous match, and this lapse followed the same pattern — a defender whose difficult start to life at City shows no sign of easing.
City responded. Iliman Ndiaye fired a shot onto the post, and Villa keeper Zion Suzuki denied the visitors on several occasions before the break.
Haaland levels, then Donnarumma's moment
The equaliser arrived in the 52nd minute. Erling Haaland headed home an Iliman Ndiaye cross to pull City level and seemingly restore order.
It lasted eight minutes. Villa broke down their right in the 60th minute, Ibrahim Mbaye found space and picked out Jackson on the edge of City's penalty area. Jackson's powerful low shot should have been routine for Gianluigi Donnarumma, whose specialty is shot-stopping. Instead, the keeper made a mess of his attempted save and the ball squirmed under him to restore Villa's lead.
City's seven-game winning run in the Premier League was over. A first defeat of the campaign, and two individual errors that Maresca will know can be rectified.