Newcastle have put an end to Chelsea’s 23-match-unbeaten run on Saturday with a 2-1 win over the Premier league leaders.
On the other hand, Manchester City won their own game by beating Everton one nil thereby cutting Chelsea’s Premier league lead to a mere 3 points.
Newcastle took the lead when Cisse slotted in after Gary Cahill missed Sammy Ameobi’s low cross.
An Eden Hazard shot hit a Newcastle upright before Moussa Sissoko set up Cisse for another tap-in.
The hosts had Steven Taylor sent off but, despite Didier Drogba pulling one back, held on for the win.
Chelsea piled forward late on and striker Diego Costa had a shot tipped over by 21-year-old goalkeeper Jak Alnwick, who was making his debut having come on as a half-time substitute for the injured Rob Elliot.
Mourinho had insisted that it was “impossible” to remain unbeaten all season and he was proven right as his side were frustrated by a disciplined and organised Newcastle side, much in the way they were in a goalless draw at Sunderland last weekend.
Before the break, Chelsea were limited to a couple of Willian strikes wide, a Cahill header over and a well-struck Oscar overhead kick past the frame of the goal.
The hosts gradually grew in confidence as they quelled the Blues’ threat and might have taken a surprise lead.
Ameobi found Ayoze Perez and his sliding pass released Colback, but the midfielder was thwarted when Chelsea keeper Thibaut Courtois saved his close range shot with a foot.
Chelsea exerted enough pressure but, 38 seconds after a Hazard shot came back off a post, Newcastle extended their lead when Cisse scored after a swift counter-attack.
A Taylor foul on Andre Schurrle earned the defender his second yellow card left the Magpies a man down.
And, in a dramatic finale, Drogba gave Chelsea hope when he nodded in a Fabregas free-kick.
However, Newcastle stood firm as Mourinho was left still searching for his first win at St James’ Park in five attempts as Chelsea manager.
