The first Verona derby in 11 years was won by Chievo as Hellas lost their perfect home record this season against their city rivals.
Hellas were looking for their seventh win in seven games at home this season but it was Chievo, on Eugenio Corini's return as coach having successfully saved the club from relegation last season, who stole a 1-0 victory deep in second-half stoppage time.
The away team did most of the attacking in a tight encounter at the Stadio Marc'Antonio Bentegodi, and they finally found a way through in the last minute of stoppage time when Dejan Lazarevic struck the winner.
Just five minutes in, the derby seemed to be heading in the right direction for the official visiting team when Cesar had the ball in the back of the net but an offside flag was raised to cut short his joy.
Chievo were already looking keener to attack than they had been under Corini's predecessor Giuseppe Sannino and Ivan Radovanovic had their second effort of the game in the 17th minute, just missing the target from the edge of the area.
Hellas for their part were playing a waiting game, rarely getting the ball forwards to Luca Toni as Chievo continued to send shots in on Rafael's goal, Alessio Sestu next to miss the target.
Marcelo Estigarribia became the third Chievo player to miss the target but at least the positive signs were there for Corini, not that the home fans were so enthusiastic.
The first chance of the second half also went Chievo's way with Cyril Thereau finding himself with only Rafael to beat, but he poked his shot wide a little too hastily.
Verona defender Michelangelo Albertazzi saved his side by closing Radovanovic down as Chievo kept up the pressure.
It did not seem like they were going to be rewarded until Acosty got to the goal line in the third minute of stoppage time and pulled the ball back towards Lazarevic.
The former Torino forward coolly supplied a finish from 10 yards out, nonchalantly defying the pressure on his shoulders at such an advanced moment in the game to snatch victory which, on balance, was deserved.