Olivier Giroud opened the scoring for Arsenal with a glancing header in the 28th minute before James Morrison's superb volley got West Brom their equaliser in the 28th minute.
Manchester City, Arsenal stunned, Chelsea win
Arsenal suffered their third loss of the English Premier League campaign in a 1-2 defeat to West Brom.
Mikel Arteta who came in for an injured Francis Coquelin who left the pitch with a knee injury in the 14th minute, scored an own goal gave the Baggies the lead five minutes before the break
Arsenal had the chance to level towards the end of the game but Santi Carzola slipped as he took a penalty which went off the mark.
Chelsea recorded their first win in over month after their narrow edge over Norwich in the fixture played simultaneously with the Arsenal game on Saturday November 21.
Jose Mourinho's men struggled to break down Norwich in the first as they went into the half time goaless.
Diego Costa ended his goal drought to net Chelsea's winner in the 64th minute following a quick free-kick from Cesc Fabregas.
Jose Mourinho returned to the dugout following his stadium ban during the last game against Stoke City.
Norwich had opportunities of their own but failed to find their killer touch as they suffered defeat.
The biggest shock came at the Etihad as Manchester City were soundly beaten at home by Liverpool.
Eliaquim Mangala opened the scoring for Liverpool by diverting the ball past Joe Hart in the seventh minute before Philippe Coutinho and Roberto Firmino added to their side's lead to give Jurgen Kloop's men a 3-0 lead in to half time.
Sergio Aguero scored a consolation goal on his return from injury but City could not launch successful comeback as Martin Skrtel added another one for Liverpool.
Other EPL Results
Watford 1 Vs Manchester United 2
Everton 4 Vs Aston Villa 0
Newcastle 0 Vs Leicester City 3
Southampton 0 Vs Stoke City 1
Chelsea 1 Vs Norwich 0
West Brom 1 Vs Arsenal 2
Swansea 2 Vs Bournemouth
Man City 1 Vs Liverpool 4
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