Chelsea head coach Maurizio Sarri has revealed that Mateo Kovacic is currently not ready to complete 90 minutes.
Kovacic has arrived at Stamford Bridge as part of the deal which has taken Thibaut Courtois to Real Madrid, but the Serbia international was not involved as Chelsea defeated Huddersfield Town last weekend.
Sarri has suggested that the 24-year-old is not yet match fit, but could be used off the bench when Chelsea face Arsenal at Stamford Bridge on Saturday evening.
At a press conference, the Italian told reporters: "I think Mateo will be very useful for us. At this moment he has to work, he is not ready for 90 minutes but maybe tomorrow for the last 30 minutes. I ask a lot for him, because for me is a very good player and in my opinion he can improve more.
"I think he can play in the three midfielders, it is the same for him centre, left or right. He is a very good offensive player, but he has improved during two years at Real."
Kovacic made 55 starts and 54 substitute appearances during his three years at the Bernabeu.