The trophy Roman Abramovich had targeted since his 2003 takeover and won unexpectedly in May has now been surrendered like no team before it, and led to manager Roberto Di Matteo being fired last month.
Chelsea's failure to progress owes much to Torres' inability to justify his $80 million-plus price tag with goals, with only one in Group E before Wednesday.
Such is the Spain striker's decline, Benitez was left extolling the merits of his contribution in defense on the eve of the match.
But Torres was at the heart of the powerful start by the energetic hosts, who were ripping through the Danish champions with ease.
Torres had a shot pushed round the post by goalkeeper Jesper Hansen, and put the ball through to Mata who set up Eden Hazard but the resulting shot was easily saved.
There was a let off for the visitors when Nicolai Stokholm turned the ball onto his own crossbar from Victor Moses' cross.
The first penalty was awarded by referee Bas Nijhuis in the 31st after Cahill handled, but goalkeeper Petr Cech dived correctly to his right to save from captain Nicolai Stokholm.
Almost immediately at the other end, Cahill's effort was then handled by Mikkel Beckmann. But Hazard was no better from the spot than Stokholm, as he struck low to the right and Hansen saved.
Chelsea, though, got another chance when Mata struck into Joshua John's arms. This time, Luiz found the net on his return from suspension, sending Hansen the wrong way.
Torres produced a morale-boosting goal in stoppage time after first clattering an effort against Hansen but then lifting the rebound into the net.
Chelsea was sloppy at the start of the second half as John surged past Branislav Ivanovic and beat Cech.
But Chelsea's two-goal cushion was restored after Torres won a free kick and Mata curled the ball in for Cahill to head powerfully into the net in the 51st.
Torres' second came five minutes later, driving into the net after Hazard cut the ball back to him.
Chelsea was now rampant and Mata played a one-two with Hazard before turning the ball into the net in the 63rd after his first effort was blocked by Hansen's legs.
Gaps in the tiring visiting defense were exploited again as Oscar picked up possession and slotted in the sixth in the 71st.