Carlo Ancelotti's side were on course for a crucial win after late goals from Didier Drogba and John Terry, but Ciaran Clark equalised in stoppage time and the reigning champions are now in severe danger of losing touch with the main title contenders.

Even a Champions League spot isn't certain for fifth-placed Chelsea. The Blues have won just once in eight league games and are six points behind leaders Manchester United, who also have a game in hand.

Frank Lampard put Chelsea in front with a 23rd-minute penalty, but Ashley Young levelled from the spot four minutes before half-time.

Villa took the lead when Emile Heskey headed in Stewart Downing's cross in the 47th minute.

Drogba equalised in the 84th minute and it looked as though Chelsea would steal the points when Terry netted in the 89th minute.

But in stoppage time the Chelsea defence went to sleep and Clark beat the offside trap to head in the leveller.