The Blues had not allowed a single goal in the Premier League since Mesut Ozil's third in their 3-0 defeat to Arsenal on September 24, a run of 601 minutes coinciding with their switch to a 3-4-3 formation.
That clean sheet streak had stretched over six full games, starting with their 2-0 victory over Hull and running through wins against Leicester, Manchester United, Southampton, Everton and Middlesbrough.
Antonio Conte's men had conceded twice against West Ham in their 2-1 EFL Cup defeat on October 26, although key players such as Thibaut Courtois were rested.
Chelsea's outstanding run of form propelled them to the top of the Premier League table ahead of matchday 13, aided by not having European football to distract or tire them.
But Eriksen's goal, struck with aplomb 11 minutes in at home to Spurs, leaves them facing the possibility of failing to triumph in the league for the first time in over two months.
If Chelsea can muster up a comeback, they will leapfrog Manchester City and Liverpool to go top of division. Defeat would leave them two points adrift and allow Tottenham to climb up to fourth, one point off their London rivals.