Torino took full advantage of a spectacular collapse from Atalanta to claim their first away win of the Serie A season.
German Denis ensured a steady start for the hosts before Rolando Bianchi equalised from the penalty spot before half-time.
Alessandro Gazzi, Alen Stefanovic and Danilo D'Ambrosio all notched after the break, Bianchi completing the rout with his fourth goal of the season to lift promoted Torino up to sixth place.
It appeared that the first half would belong to the Bergamo side as Denis tested Jean-Francois Gillet with a fierce shot within 10 minutes.
Andrea Consigli did well to keep out a daisy-cutter from Gazzi at the other end but Atalanta soon managed to take the lead their early verve merited.
In the 28th minute, Denis danced on to a cute pass from Riccardo Cazzola to twist his body and comfortably beat Gillet.
Having dominated for much of the early exchanges, and unaware of what was to follow, Atalanta might have felt aggrieved when Torino equalised 10 minutes later.
Giacomo Bonaventura was pulled up for handball in the hosts' penalty box and Bianchi duly obliged from the spot.
Thomas Manfredini was withdrawn through injury shortly before the break but Colantuono was satisfied with his defence's efforts.
That would all change over the course of a torrid second period, though, as Torino systematically and brutally dismantled their opponents.
Angelo Ogbonna cleared the danger when Gillet mishit a clearance to Atalanta's Cristian Raimondi, with Giuseppe De Luca seeing his goal ruled offside, but the 45 minutes belonged to the visitors.
Gazzi nudged Giampiero Ventura's men into the lead as he beat Consigli from a corner in the 63rd minute.
Stefanovic rifled the ball home from distance three minutes later, following good work from Alessio Cerci, and Torino made it 4-1 in the 73rd minute.
With Atalanta's defence still in tatters, D'Ambrosio gratefully nodded past a stranded Consigli.
Bianchi completed Atalanta's humiliation only three minutes later, the home back line nowhere to be seen as the former Manchester City striker found the back of the net with a low drive.