Query: What competition sparked the rivalry with Manchester?
Context: Other rivalries within London include those with Chelsea, Fulham and West Ham United. In addition, Arsenal and Manchester United developed a strong on-pitch rivalry in the late 1980s, which intensified in recent years when both clubs were competing for the Premier League title – so much so that a 2003 online poll by the Football Fans Census listed Manchester United as Arsenal's biggest rivals, followed by Tottenham and Chelsea. A 2008 poll listed the Tottenham rivalry as more important.