Chelsea boss Jose Mourinho believes that the competitive nature of modern football means that nobody will match Arsenal's unbeaten 2003-04 Premier League campaign.

The Gunners went the entire season without losing a game as they romped to the league title, a feat that many believe Chelsea could repeat this year.

"It's something that happened once in a lifetime," Mourinho is quoted as saying by Sky Sports News. "I don't see, in modern football with the competitiveness of this Premier League, one team being champion without a defeat.

"That will stay in the history as the second and the last time.

"[That is] my opinion, but we don't know."

The only other team to go an entire season unbeaten were Preston North End in the 1880s.