Chelsea will be without striker Diego Costa for their Champions League clash at home to Maribor in London on Wednesday.
"He hasn't trained because he's not in condition to do so," manager Jose Mourinho told a news conference on Monday.
"It's the same problem that he is having, it's simple. Let's see what happens for the next weekend."
Costa, who has made a stunning start to his Chelsea career with nine Premier League goals since joining from Atletico Madrid, has been struggling with a hamstring injury and did not play in the 2-1 defeat of Crystal Palace on Saturday.
Chelsea are well-placed in Group G with four points from their opening two fixtures but have several players unavailable for the visit of the Slovenian outsiders to Stamford Bridge.
Midfielders John Obi Mikel, Andre Schurrle and Ramires will all play no part while striker Didier Drogba is not fit enough to play for 90 minutes, according to Mourinho.
"Mikel made a big effort to be available for the weekend. He came back from the national team with a foot problem. He can't play tomorrow," he said.
"Didier is not in condition to play 90 minutes but he can play."
He confirmed that 17-year-old reserve team striker Dominic Solanke would start on the bench.
