A last-gasp goal from Davide Moscardelli ended Genoa's unbeaten start to the season and took Chievo above them in the Serie A table.
The Chievo sub scored with practically the last kick of the game to take the Flying Donkeys above their opponents amongst the early frontrunners after Rodrigo Palacio had put the visitors in front early in the second half and Sergio Pellissier had levelled 15 minutes from time.
Genoa played the last half an hour with 10 men after Dario Dainelli was sent off for giving away a penalty, which Sebastien Frey saved from Pellissier.
Genoa's in-form midfielder Miguel Veloso got in the first shot on Stefano Sorrentino's goal in the 14th minute, but the Chievo goalkeeper pushed the ball wide of his post.
Three minutes later, Rinaldo Cruzado tried his luck from distance with a shot which would have beaten Frey had it been on target.
The best chance of the first half fell at the feet of Luca Rigoni after half an hour, but his shot was saved by Frey with only the Genoa goalkeeper to beat.
Palacio put Genoa in front three minutes into the second half with his fourth goal of the season.
He showed excellent upper-body strength to hold off Santiago Morero and then keep his composure to beat Sorrentino with a shot low into the bottom right-hand corner.
The league leaders going into today were looking comfortable until a dubious penalty decision saw them reduced to 10 men with Dainelli sent off for a foul on Pellissier in the 59th minute.
The Chievo forward was falling to the ground with the ball heading comfortably into the arms of Frey, but as Dainelli cut round behind the Chievo striker, referee Carmine Russo saw him clip Pellissier's heel.
Justice was seemingly done when Frey made a fine one-handed save to deny Pellissier from the spot, but the damage caused by Dainelli's red card was irreparable.
Palacio was sacrificed as Genoa coach Alberto Malesani sent on another defender in Andreas Granqvist, but the Rossoblu defence was unable to see out the final 20 minutes unscathed.
Pellissier made up for his penalty miss with a textbook header into the top left-hand corner from a right-wing corner, levelling matters in the 74th minute.
And the Flying Donkeys surged forwards in search of a winner, which they found in the third minute of stoppage time when Moscardelli headed in from eight yards out.
