Marko Livaja grabbed a late winner as Atalanta saw off the challenge of Bologna at the Stadio Atleti Azzurri d'Italia.
The Croatian forward scored with practically the last kick of the game to seal a 2-1 win for Stefano Colantuono's men after Davide Brivio's goal had been wiped out immediately by Rolando Bianchi.
The win lifts the Nerazzurri three points clear of AC Milan in mid-table and leaves Bologna just a point above the drop zone on Sunday night.
After a tight opening, Atalanta started to assert themselves on the game and a prolonged spell of pressure led to Giulio Migliaccio sending the first shot of the game over the crossbar.
Bologna lacked ambition and only once threatened in the first half with Alessandro Diamanti's free-kick picking out Sorenson, whose header was tipped over the bar, albeit after the referee's whistle had been blown for a foul by the Bologna defender.
Atalanta could have taken the lead in the 58th minute when a bad backpass was pounced on by Guido Marilungo, but with only the goalkeeper to beat, the former Sampdoria forward placed his shot wide.
Brivio showed better accuracy from a much harder position to give the home team the lead in the 74th minute.
Most of the players were expecting a cross as he burst down the left wing, but he had other ideas as he sent a low shot into the far corner of Gianluca Curci's goal.
Bianchi was sent on and, within minutes, he opened his Bologna account against the side where his Serie A career commenced.
He headed in after Jonathan Cristaldo's header cannoned back off the crossbar, granting the former Torino forward one of his easiest goals, although he did not endear himself to his former fans by celebrating in front of them.
The game appeared to be heading for a draw until Livaja unleashed a shot from 25 yards which seemed to be heading straight at Curci.
However, the Bologna goalkeeper reached out a weak hand and only pushed the ball into the roof of his own goal as Atalanta snatched victory in the third minute of stoppage time.