Kurt Zouma and Eden Hazard gave Chelsea a controversial 2-0 win over nine-man Arsenal as the simmering feud between the bitter rivals boiled over with red cards for Gabriel and Santi Cazorla.
Watford heaped more misery on former England manager Steve McClaren with a 2-1 win at Newcastle while Bournemouth managed their first ever Premier League home win in beating Sunderland 2-0 yesterday.
The acrimonious relationship between Chelsea manager Jose Mourinho and Gunners boss Arsene Wenger seeped through to both teams at Stamford Bridge in a tetchy London derby featuring even more flashpoints than usual.
Wenger was furious Mike Dean opted not to send off Diego Costa following a clash with Laurent Koscielny and the referee further infuriated the Frenchman when he dismissed Gabriel for kicking Costa and then showed Cazorla a red card in the second half.
"I would not like to be Mike Dean tonight. Costa twice should be sent off," Wenger said.
"In every game Costa has aggravation and he gets away with it because of the weakness of the referee.
"Gabriel should not have responded but the two sending offs for us and Costa staying on the pitch is a shame (shameful)."
Mourinho's response felt designed to provoke Wenger as he said: "I don't have a view on the sending off. Man of the match for sure was Diego Costa. He brought everything to the game."
A surly pre-match handshake between old rivals Wenger and Mourinho set the tone for a feisty clash.
Chelsea striker Costa was booked for shoving over Laurent Koscielny after whacking the Arsenal defender in the face moments earlier.
Gunners defender Gabriel remonstrated with Costa and was booked for his complaints.
But the Brazilian couldn't keep his emotions under control and in first-half stoppage-time he aimed a sly kick at Costa right in front of the referee, who immediately brandished a red card.
Chelsea made their numerical advantage count in the 53rd minute when French defender Zouma was left unmarked to head in a Cesc Fabregas free-kick.
Cazorla was sent off in the 79th minute when the Spanish midfielder caught Fabregas with an ugly lunging tackle.
Belgium midfielder Hazard guaranteed the champions' second league victory of the season in the 90th minute when his strike deflected off Calum Chambers to leave the Gunners without a league success against the Blues since 2011.
