The 2003–04 season was Chelsea F.C.'s, 12th consecutive season in the Premier League and 98th year as a club. Manager Claudio Ranieri was sacked on 31 May 2004 and was replaced by José Mourinho. In July 2003, long-time chairman Ken Bates sold the club to Russian billionaire Roman Abramovich.
Chelsea finished second to the unbeaten Arsenal in the Premier League. In the Champions League Chelsea reached the semi-finals against AS Monaco, but failed to reach the final, losing 5–3 on aggregate to the French side. They also exited the FA Cup in the fifth round to Arsenal and the Carling Cup in the quarter-finals to Aston Villa.