Premier League champions Chelsea won only their second league game this season against nine-man Arsenal in a fiery match at Stamford Bridge. Saido Berahino scored on his first start since threatening to go on strike as West Brom beat a lacklustre Aston Villa in a West Midlands derby. Bournemouth won their first Premier League game at home - a result that saw Sunderland slip to bottom place. Newcastle's winless start to the season continued as Odion Ighalo's double led Watford to a second successive victory.