Assaidi's wonder strike condemns Mourinho's Chelsea to away defeat
Oussama Assaidi stunned Chelsea with a superb 90th-minute winner as Stoke claimed their first league victory over the Blues in 38 years.
The on-loan Liverpool winger came on as a substitute six minutes from time and his first real contribution was to pick the ball up on the left, cut inside and unleash a ferocious shot into the top corner.
Jose Mourinho's first trip to the Britannia Stadium began well as Andre Schurrle gave Chelsea a 10th-minute lead.
But Peter Crouch levelled three minutes before half-time, and five minutes after the break Stephen Ireland put the hosts ahead.
Schurrle quickly equalised with another fine finish and it looked like both sides would have to settle for a point until Assaidi's brilliant intervention earned a 3-2 victory.
Stoke's last win over Chelsea came in the League Cup in 1995 when Potters manager Mark Hughes was in the Blues side, while their most recent league victory was in 1975.
The result ended Chelsea's three-match winning run and saw them drop below Liverpool into third, while leaders Arsenal now have the chance to open up a seven-point gap on Sunday.
Schurrle was one of two changes to the Chelsea side from Wednesday's win over Sunderland and he was soon into the action, pulling the ball back for Ramires, who shot well over the bar from 10 yards out.
The Brazilian should have done much better, but the visitors only had to wait until the 10th minute to take the lead.
This time Schurrle did it all himself, picking the ball up in midfield, holding off Ryan Shawcross and Glenn Whelan before shooting across Asmir Begovic and into the bottom corner.
It was Schurrle's second Premier League goal, and Chelsea had plenty of chances to add to their lead.
Juan Mata shot straight at Begovic in the 16th minute after a free-kick fell to him on the edge of the box, while the Spain international then failed to pick out Fernando Torres in the centre after Jonathan Walters had given the ball away.
Ramires was the man most culpable, the midfielder having three further efforts during the first half but failing to really test Begovic.
Stoke had been forced into a change in the 18th minute when Charlie Adam, their main creative force, limped off and was replaced by Ireland.
The Potters were showing some decent play in midfield but their final ball was lacking and front man Crouch was isolated.
They had their first chance in the 38th minute when Steven Nzonzi found Marko Arnautovic on the left and his cross picked out Walters at the back post, but the Republic of Ireland man, who last season scored two own goals and missed a penalty in the same fixture, could only nod wide.
The equaliser came from a break instigated by Geoff Cameron, who found Walters down the right.
His cross was just out of the reach of a diving Ireland but Arnautovic won a corner and his delivery was turned in by Crouch.
Chelsea had only themselves to blame, with Mikel leaving Crouch unmarked and Petr Cech opting to come off his line but getting nowhere near the ball.
Stoke carried the momentum into the second half and stunned Chelsea by taking the lead in the 50th minute.
Walters broke down the right and squared the ball for Ireland, who took one touch to control before curling a precision shot in off the far post.
The Britannia roared its approval but Stoke were ahead for just three minutes, and it was Schurrle again.
A Mata free-kick was half cleared by Crouch to the German on the edge of the box, who once again produced a clinical finish into the far corner.
Schurrle almost completed his hat-trick in the 57th minute but although he beat Begovic again his curling shot bounced off the bar.
Both teams were committing men forward, and 10 minutes later it was Stoke's turn to go close.
Nzonzi crossed for Crouch, who set up Ireland in space eight yards out but this time he could only curl his shot high and wide.
Schurrle's hat-trick hopes were ended as Mourinho sent on Frank Lampard and Samuel Eto'o, and the latter swiftly had a sight of goal but poked his shot just wide.
Marc Muniesa gave away a free-kick on the edge of the box for a foul on Demba Ba, but Begovic was safely behind Lampard's shot, which found its way through a 10-man wall.
Walters was booked for shoving John Terry in the chest and was swiftly replaced by Assaidi and his strike handed Mourinho his first ever Premier League defeat in December.