With 90 minutes played, it looked as if Chelsea were to draw away 1-1 for the third time in this group stage but then the home team struck a sickening blow, scoring from a corner to leave just a point covering the top three sides going into the final games.
After a largely forgettable first half in which Michael Ballack had hit woodwork for the Germans, again from a corner, it was Didier Drogba who fired the Blues ahead early in the second half.
Cech then kept Ballack out with two fine saves but it still proved a lead Andre Villas-Boas's side could not hold onto, Leverkusen equalising with 72 minutes played of what had been a fairly even encounter. Chelsea had chances to restore the lead but it was Leverkusen who tool theirs.
A win or a 0-0 draw at home to Valencia in two weeks' time is now imperative.