A wonderful strike from Agim Ibraimi was enough to secure a sensational point for Maribor, as they halted the Chelsea train in it's tracks, as last season's runners-up were unable to capitalise on a host of big chances.
Ibraimi will take the headlines in Slovenia, as the Macedonian midfielder put a stunning curling effort past Petr Cech, before Nemanja Matic poked the visitor's back level with 15 minutes to go. Star player Eden Hazard had a fantastic chance to win it for the Blues right at the death, when he was brought down in the box, though Jasmin Handanovic was on hand to keep it out, sparking ecstatic scenes of jubilation in the Ljudski vrt.
Chelsea started the game rather slowly, struggling to break down a resilient Maribor defence, a shadow of the Slovenian side's spineless self in their 6-0 drubbing at Stamford Bridge two weeks ago.
The first real chance fell to Chelsea however, as Kurt Zouma headed a perfect Cesc Fabregas cross just over from distance. Maribor had an even bigger chance straight up at the other end though, when Morales Tavares somehow managed to get away from three Chelsea defenders, before playing through teenager Luka Zahovic, but the son of Slovenian legend Zlatko couldn't beat Kurt Zouma on the line.
In an attempt to grab the crucial opener, Mourinho made two substitutions during the interval, bringing on new signing Diego Costa and Oscar, for Willian and Andre Schurrle.
The tactical shake-up didn't do much though, as Maribor took a shock lead just five minutes into the second-half. After a swift counter-attack from the hosts, a cross was sent in, which the Chelsea defence failed to deal with and the loose ball fell to the unmarked Ibraimi on the edge of the box and the 26-year-old sent a sublime shot, curling into the far post, leaving Petr Cech well beaten and Chelsea shell-shocked.
Mourinho responded instantly, completely ditching the typical 4-2-3-1 formation normally associated with Chelsea and bringing Ramires on for Filipe Luis, leaving the Blues with three at the back - and that very nearly cost them. When Zahovic received a wonderful cross, the youngster failed to land the fatal blow and jarred his shot well over the bar from six yards.
Chelsea finally found their vital equaliser with 20 minutes to go, whern John Terry headed down a Cesc Fabregas corner and Nemanja Matic scored one of the easiest goals he'll ever score; a tap-in to an empty net from a yard out.
The Blues had a wonderful chance to win it right at the death, as the marvellous Eden Hazard was brought down in the box by Mitja Viler, after a tricky run, though Maribor supporters couldn't believe their eyes, as Jasmin Handanovic got down to his left to keep out the Belgian's spot-kick, to send the crowd into a state of euphoria.
Chelsea stay top of the group, three points clear of second-placed Schalke, after the German side's 4-2 defeat to Sporting Lisbon. Meanwhile, Chelsea have equalled their 2005/06 record of going unbeaten in their first 16 games, a remarkable achievement, as Jose Mourinho's side continue to challenge for silverware on every front.