Dele Alli ended 28 years of hurt for Tottenham by leading them to their first win at Chelsea since 1990, winning there for the first time since February 1990.
Chelsea scored the first goal in a Premier League home game and went on to lose for the first time since April 1st 2017 against Crystal Palace (1-2).
Spurs were a goal down before a stunning equaliser from Christian Eriksen was followed with a quick fire double blast from Alli in the second half.
And to rub it in Tottenham are now a whopping eight points clear of Chelsea in fourth place and have all but ended their hopes of playing Champions League football next season.
There are only seven games remaining for Chelsea to make up ground and try to catch Spurs or face being condemned to the Europa League next season.
Alli cashed in on two horrendous pieces of defending to turn the match on its head in four minutes.
He first squeezed between Chelsea centre half’s Andreas Christensen and Cesar Azpilicueta to latch onto Eric Dier’s through ball in the 62nd minute before stabbing it past stand-in keeper Willy Caballero.
And then Chelsea got in a terrible mess trying to clear a shot from Spurs’ striker Son only for Alli to pounce and poke home a shot from close range.
The defeat is revenge for Tottenham after they drew 2-2 here two years ago to see their title hopes ended.
And it is an unmitigated disaster for Chelsea, but they are unlikely to sack manager Antonio Conte immediately.
They still have an FA Cup semifinal with Southampton later this month which means a chance of a trophy.