Chelsea manager Jose Mourinho says he is going through the worst period of his managerial career with his team winning just four of their 11 matches this season.The Premier League champions currently sit 14th in the table after seven games, having just won twice in the league.It is the kind of position they regularly occupied before the arrival of billionaire Roman Abramovitch in 2003, but one that younger Chelsea fans are unused to seeing them in.Chelsea, who kept 17 league clean sheets last season, have kept just one so far against Arsenal, and have conceded 14 goals. Only Sunderland, who are bottom, have let in more in the league.Also read: Mourinho may be sacked as Chelsea manager, says ex-defender le Saux No team has allowed their opponents more shots on target than Chelsea, while Saturday’s opponents Southampton have allowed the fewest in the league this season.”I define this as the worst period in my career. It’s a fantastic experience, even though I don’t want to repeat it again,” Mourinho told reporters at the club’s training ground at Cobham, south of London.”Players know when they make mistakes. I don’t know what it’s like in your offices, but nobody seems to care about your mistakes,” he said.Mourinho refused to be drawn on the subject of Eva Carnero, the former first team doctor who quit after being criticised by the manager. Although he was cleared by the FA of discriminatory charges against the doctor, FA chairman Greg Dyke said on Thursday Mourinho was in the wrong and should have apologised.advertisement”I’m not going to comment, one day I will but not today,” the 52-year-old said.