Two costly errors by John Mikel Obi sent 10-man Chelsea crashing to shock defeat to Serie A strugglers Roma.
The hosts stormed into a three-goal lead inside 58 minutes thanks to Christian Panucci and two goals from Mirko Vucinic.
Chelsea reduced the deficit through captain John Terry in the 75th minute but it was not enough to save them from a humiliating defeat, their worst in Europe since their 5-1 extra-time thrashing by Barcelona in 2000.
Their miserable night ended in more woe with Deco dismissed for a second bookable offence in the 80th minute.
A cagey start by both sides was brought to an end when Deco tried his luck from 25-yards but the Chelsea midfielder was thwarted by a fine save from Doni.
A clever run down the left flank by Florent Malouda should have resulted in a clear opening for Nicolas Anelka but the Chelsea striker just failed to connect with his pass.
Chelsea were having the best of the opening exchanges Frank Lampard and Deco controlling the game in midfield.
Another run down the left by Malouda provided Deco with a chance to open the scoring but this time his 20-yard effort was deflected for a corner. But for all their initial domination, the English side could not convert their superiority into goals.
Lampard forced Doni into a fine save by his near post when he let fly from 20 yards in the 21st minute.
On the half-hour Deco set up Lampard for another shot on goal but the England midfielder was again denied by the agility of Doni in the Roma goal.
Roma had posed little threat to the English side but a poor pass from Mikel forced Deco to bring down Francesco Totti, resulting in a yellow card for the midfielder.
Chelsea paid a heavy price for Deco's actions as Roma went ahead in the 33rd minute through former Blue Panucci.
Cicinho's cross from the right wing eluded everyone and Panucci reacted first to sweep the ball into the net beyond Cech from close-range.
But the changes had little time to take effect before Vucinic put Roma two in front three minutes after the re-start. The Roma midfielder took a short pass from Brighi and sent a rising 25-yard drive into the net beyond the despairing Cech.
Roma went three in front in the 58th minute when Mikel made another astonishing error. The Nigerian lost the ball to Vucinic, who ran the length of the Chelsea half, beat the retreating Mikel again, and fired home beyond Cech.
But Chelsea finally reduced the arrears when captain Terry tucked the ball home from close range after Deco's shot had been deflected into his path.
But the night got worse for Chelsea when Deco was sent off for a second bookable offence with 10 minutes remaining.