William Gallas broke Tottenham's hearts and resistance with an injury-time winner at Stamford Bridge.
Gallas goal was sweet for Chelsea - but hard on Spurs
Gallas curled a spectacular shot around Paul Robinson to tighten Chelsea's grip at the top of the Premiership.
Chelsea went ahead when Michael Essien tucked away his first goal for Chelsea from Shaun Wright-Phillips' low cross.
Jermaine Jenas scored a deserved equaliser for Spurs when he reacted first to Michael Dawson's knock-down to nick the ball past Petr Cech.
On Chelsea's lush, newly-laid pitch, Wright-Phillips made a good early impression as he sought make the most of a rare Premiership start.
The England man held the ball up well for Crespo to fire a dangerous ball across the Spurs box, before Mido's ferocious shot from a narrow angle sparked a spell of intense Tottenham pressure.
Chelsea rode out that storm and Wright-Phillips soon stormed forward again to draw a great save from Paul Robinson. The ball ran free to Essien who stabbed the ball wide of the open goal from 10 yards.
And inevitably, Wright-Phillips was eventually at the heart of Chelsea's opener.
He latched on to a suicidal square pass by Michael Carrick, and his low cross was dummied by Crespo and found Essien who tucked the ball away from eight yards.
The goal helped Chelsea settle into a better rhythm, with Spurs to some degree architects of their own downfall as they consistently gave the ball away cheaply.
Carrick was the culprit for the goal, but he did make amends with a beautifully delivered free-kick for Spurs' equaliser.
Dawson won the aerial battle with Robert Huth and Jenas reacted first to his nod-down to steal in and prod the ball past Cech.
Chelsea's players and staff celebrate their late winner
After half-time, full-back Lee Young-Pyo was patently under instruction to curb his attacking instincts, and that helped Spurs contain Wright-Phillips.
Indeed the visitors - with Dawson especially stoic - were managing to keep the Blues at bay, although when Lampard spread play superbly for Crespo to whip in a cross, Ledley King sliced his attempted clearance on to the roof of his own net.
And from Lampard's resulting corner Terry's towering header was acrobatically palmed over by Robinson.
At the other end, King's raking pass sent Jenas clear but the midfielder's weak finish allowed Cech to save.
But just when it looked like Spurs would become only the second side this season to deny Chelsea Premiership victory at Stamford Bridge, up stepped Gallas.
Cutting in from the left, he curled a super shot round a helpless Robinson to leave Spurs still looking for their first league win over Chelsea in 16 years.
Chelsea defender William Gallas on Jose Mourinho's goalscoring celebrations with his players:
"Some people like him, some people don't but he's a good manager and we're all behind him.
"We want to win everything for him , we want to win the Premiership and the FA and hopefully next season we'll win everything."
Spurs coach Chris Hughton:
"It was heartbreaking but we're still upbeat about finishing in fourth place and the performance.
"We started very bright, did well on the counter-attack and in the second half we looked solid and cope fairly well.
"We came up against the best team in the country and most people would say we deserved something from the game."
Chelsea: Cech, Paulo Ferreira, Huth, Terry, Gallas, Makelele,
Wright-Phillips (Drogba 68), Lampard, Essien (Maniche 77),
Joe Cole (Duff 68), Crespo.
Subs Not Used: Del Horno, Cudicini.
Booked: Duff, Drogba.
Goals: Essien 14, Gallas 90.
Tottenham: Robinson, Stalteri, King, Dawson, Lee, Jenas,
Carrick, Davids, Tainio, Mido, Keane (Defoe 83).
Subs Not Used: Murphy, Cerny, Lennon, Gardner.
Goals: Jenas 45.
Ref: G Poll (Hertfordshire).