Former Chelsea midfielder Michael Ballack has hailed the Antonio Conte effect after a stunning first half of the season at Stamford Bridge.
Italian boss Conte has taken the side, who struggled so badly under Jose Mourinho last season, and guided them eight points clear at the top of the Premier League.
And Ballack, who racked up over 150 appearances in West London, has been impressed by the way Conte has taken the title race by the scruff of the neck in his first season in England.
"The surprise was, last year, that they were so bad,'' Ballack said.