Benfica maintained their five-point lead at the top of the Primeira Liga after Lisandro Lopez's last-gasp header pegged back rivals Porto for a 1-1 draw.
The Estadio do Dragao was in a party mood as stoppage time ticked around, only for Lopez to have the final word.
On as a first-half substitute for injured skipper Luisao, the defender found enough space to steer a cross from Andre Horta past Iker Casillas after a short corner.
Porto led five minutes into the second period through a fine strike by Diogo Jota.
The 19-year-old collected Jesus Manuel Corona's pass in space on the left-hand side of the penalty area, darted into space down the outside of Nelsinho and finished impressively across Ederson Moraes from an acute angle.
Casillas kept out a rasping drive from Andreas Samaris and Benfica were destined for a first league defeat of the season until Lopez's late intervention.