Andre Villas-Boas' side desperately needed a win at the Cristal Arena to ease the pain of a miserable week that started with a stormy defeat against QPR, featuring allegations that John Terry racially abused Hoops defender Anton Ferdinand, and ended with a shocking 5-3 loss at home to Arsenal.
The Blues were on course to restore the feel-good factor when Ramires fired them into a first half lead, but David Luiz missed a penalty just before half-time and Jelle Vossen made him pay with a second half equaliser.
Chelsea squandered several chances to snatch a winner and, although they still lead Group E by two points from Bayer Leverkusen, they need at least one more win from their last two games to reach the last 16.
England captain Terry strongly denies the racism accusations but the FA have launched a probe and the Metropolitan Police are also investigating the allegations after a complaint from a member of the public.
To make matters worse for Terry, Villas-Boas decided to take his skipper out of the limelight after a shaky display against Arsenal and he was consigned to the bench alongside Frank Lampard and Juan Mata.
Even without that trio and the injured Didier Drogba, Chelsea were firm favourites to beat the Belgian champions, who were crushed 5-0 by the Blues last month.
But Chelsea's defending has been unusually slack recently and they were almost caught out when Khaleem Hyland, left completely unmarked, headed straight at Petr Cech.
Villas-Boas's side gradually found some momentum and took the lead with their first incisive attack in the 25th minute.
Ramires surged forward from halfway inside the Genk half and played the ball into Fernando Torres.
Torres clipped a clever return pass between two defenders for Brazil midfielder Ramires to fire low past Laszlo Koteles from a tight angle for his first Champions League goal.
Ramires's goal sparked Chelsea into life. Torres drove a long-range effort just wide and Ramires headed wide before Raul Meireles hit the bar with a thunderous strike from 25 yards.
The Blues should have been further ahead just before half-time as Thomas Buffel gave away a penalty with a needless handball from Florent Malouda's cross.
Luiz stepped up for the spot-kick in the absence of regular taker Lampard, but the Brazilian defender's shot was pushed away by Koteles.
Chelsea's confidence seemed to be shaken by Luiz's miss and Genk were well on top after the break.
The hosts threatened when Kennedy Kwanganga pounced on a miscued shot from Anthony Vanden Borre, only for Cech to save with his chest.
Chelsea were unable to stem the tide of Genk pressure and Mario Been's side equalised in the 61st minute.
Not for the first time this season, Chelsea's defending let them down as Fabien Camus burst through on the left and pulled a cross back for the unmarked Vossen to shoot past Cech.
Villas-Boas sent on Lampard, Daniel Sturridge and Mata as he looked to snatch a winner, but he was cursing again in the 72nd minute when Meireles squandered a glorious chance, heading straight at Koteles from 10 yards out.
Incredibly, Lampard missed an even better chance when he side-footed Sturridge's cross wide from point-blank range.
The Blues would have returned home empty-handed but for Cech, who made a good stop in the closing moments to deny Anthony Limbombe.
Source: AFP
Source: AFP