Jose Mourinho has admitted that he does not yet know the identity of his strongest Chelsea starting lineup.

The Portuguese manager, who returned for a second spell as Blues boss this summer after leaving the club in 2007, has overseen Chelsea's worst start to a Premier League season in a decade, although they still sit fourth in the table following their 2-0 victory over Fulham on Saturday.

However, there has been question marks over Mourinho's transfer dealings and team selection, with the regular omission of the club's player of the season for last year, Juan Mata, raising many eyebrows.

Mourinho has defended his tactics but has conceded that he is not yet sure of his strongest XI, challenging his players to establish their place in his side with their performances on the pitch.

"Of course, I don't know," he told Chelsea TV. "But the players have to give me the answers. I cannot dig and dig and dig looking for the best team. The players must give me the answer.

"Do I have a doubt that [Branislav] Ivanovic is in this moment my right-back? I have no doubt. You see the way the guy performs. So it is up to them.

"If somebody is waiting for me to give shirts because of status and history, that's not the point. Of course, I have some doubts in some positions and I think it's normal."

Mourinho has used 19 different players in Chelsea's opening five Premier League matches, but has not yet handed £30m-signing Willian any minutes in the top flight.