Didier Drogba and John Obi Mikel have not travelled with the Chelsea squad for Tuesday's UEFA Champions League clash with Genk.
Drogba misses out after undergoing surgery to remove screws from his arm, which he broke in the build-up to last summer's World Cup.
Blues manager Andre Villas-Boas believes it was the right time to send Drogba for the operation and hopes he will be available again for the Premier League game against Liverpool on 20th November.
"We took the risk based on his domestic suspension and the forthcoming international break to remove six of the eight screws from his arm," Villas-Boas explained.
"So he's out of this game and the Blackburn game, and should be ready to return for the team when the others go away for international fixtures."
Terry in squad
Mikel has also been left behind after Villas-Boas decided to give the midfielder a rest.
Hilario is still recovering from flu but captain John Terry has made the journey to Belgium and could be in contention to start.
The Chelsea skipper sat out the home fixture against the same opponents two weeks ago as Genk went down 5-0 at Stamford Bridge.
The Blues will be looking for another three points to keep them on course for qualification to the last 16 of Europe's premier competition.
Chelsea are currently top of Group E on seven points, while Genk are bottom after claiming just one draw and two defeats from their opening three games.