Late goals by Timo Werner and Ben Chilwell earned Chelsea a 3-1 win over 10-man Southampton to go top of the table.
Trevoh Chalobah opened the scoring for Chelsea on nine minutes, heading in at the far post after Ruben Loftus-Cheek had flicked on Chilwell's corner.
Southampton equalised in the 61st minute through James Ward-Prowse's penalty, awarded for Chilwell's foul on Tino Livramento.
Werner was denied by a brilliant save from Alex McCarthy on 72 minutes, moments before Ward-Prowse was sent off for a dangerous tackle on Jorginho after a VAR check.
Werner provided the decisive moment, sliding in from Azpilicueta's cross before Chilwell volleyed in from close range on 89 minutes to secure the victory.
Chelsea are on 16 points, two clear of Liverpool having played a match more, while Southampton drop to 17th on four points.
See: Chelsea report | Southampton report
Next fixtures
Chelsea: 16 Oct v Brentford (A)
Southampton: 16 Oct v Leeds (H)
Match officials
Referee: Martin Atkinson. Assistants: Peter Kirkup, Nick Hopton. Fourth official: Jarred Gillett. VAR: Mike Dean. Assistant VAR: Ian Hussin.
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