The European champions went in advance against the run of play while Hakim Ziyech's snap shot caught Robert Sanchez within the Brighton purpose through marvel.
But the Blues have now just one in all their ultimate seven league video games as Adam Webster's towering header earned Brighton a fully deserved point.
Thomas Tuchel become crucial of his ahead players after a 1-zero defeat at Manchester City on Saturday, however kept religion with Romelu Lukaku and Ziyech in assault as Timo Werner and Kai Havertz were once more left at the bench.
There was little to electrify the German another time as Chelsea's stoop leaves them searching over their shoulders on the contenders for a top-four end in place of a name project.
They stay 0.33 within the desk, 12 points at the back of leaders Manchester City having performed a sport extra.
Brighton have most effective gained two times of their ultimate sixteen league games, but once again just lacked the slicing area to their astounding construct-up play.
After a shiny establishing, the hosts have been hit with a sucker punch while Ziyech justified his inclusion with a effective low effort that Sanchez must have accomplished higher to shop down to his left.
Callum Hudson-Odoi wasted a first rate risk to double Chelsea's lead simply earlier than the spoil while he was positioned via by means of Lukaku in one of the Belgian's few efficient moments.
Brighton were again quicker out of the blocks after half-time and Kepa Arrizabalaga did brilliantly to show Alexis Mac Allister's deflected shot onto the post.
