Chelsea were unable to sufficiently recover from the weekend defeat to Arsenal as they were held 1-1 by Genk in Champions League Group E.
Andre Villas-Boas chose to omit John Terry and Frank Lampard from his starting XI, but the Blues took the lead in the Cristal Arena following a period of first-half dominance.
Some neat interchange on the edge of the opposition box between Ramires and Fernando Torres led to the former firing Chelsea in front from a tight angle.
The damage could have been far greater before half-time but for Raul Meireles' shot not hitting the crossbar and David Luiz converting a penalty.
The Blues were awarded the spot-kick following a handball from Thomas Buffel but Luiz's effort was well saved by Laszlo Koteles down to his right.
Genk increased the tempo in the second period in search of an equaliser and they got their just rewards when Jelle Vossen slotted a pull-back from Fabien Camus past Petr Cech from eight yards.
Chelsea did, though, have chances to snatch three points but Lampard and Florent Malouda spurned their opportunities to cap off a lacklustre performance from the west Londoners.