Chelsea have suffered a double injury blow ahead of the Premier League clash against Fulham on Saturday.
The Blues are three points ahead of West Ham United in the race for the fourth spot, and they will be aiming to extend the lead.
Kovacic returned to training after a hamstring injury, but he has suffered a fresh setback which will keep him out.
Rudiger suffered a knock in the midweek clash against Real Madrid. He is likely to return in a few days’ time.
The west London derby has been dominated by the Blues, and they are unbeaten in the previous 20 meetings.
They have won the last six encounters against the Cottagers, who are winless at Stamford Bridge since October 1979.