Fast-starting Watford inflicted Premier League champions Leicester's sixth defeat of the season with a 2-1 win at Vicarage Road.
Etienne Capoue scored after 32 seconds and Roberto Pereyra's fine strike after 12 minutes doubled the advantage.
Jamie Vardy was felled for a penalty converted by Riyad Mahrez three minutes later but Leicester never really looked like finding an equaliser as Watford responded from the 6-1 loss at Liverpool.
Claudio Ranieri's men still have more points than Chelsea - their predecessors as champions - did at the same stage last season.
With 12 rather than 11, that is small consolation considering the fact Leicester remain perilously close to the relegation zone.
The result leaves Leicester without a win in their last four matches ahead of their midweek Champions League meeting with Club Brugge at the King Power Stadium, where a point will be enough to send them into the knockout stages.
For Watford, this third win in five outings keeps up their encouraging start to the campaign under new manager Walter Mazzarri, who extended his run of games without defeat in fixtures against Claudio Ranieri to 12.
Click the video above to see all the key moments from Watford v Leicester as the hosts won 2-1 at Vicarage Road.