Ademola Lookman scored twice as Atalanta stunned Serie A leaders Napoli by winning 3-0 at the Stadio Diego Armando Maradona.
Serie A top scorer Mateo Retegui was surprisingly left on the bench but Lookman took charge as the visitors inflicted Napoli's first defeat since the opening day of the season.
Retegui was brought on with 14 minutes remaining and scored in stoppage time for his 11th goal in as many matches.
Atalanta are up to second but could be leapfrogged by Inter Milan if the defending champions beat Venezia later on Sunday.
Atalanta took the lead when Charles de Ketelaere nodded the ball for former Everton forward Lookman to slot into the bottom corner.
Napoli almost levelled immediately but Scott McTominay's powerful effort crashed off the post.
De Ketelaere then raced down the right and squirmed between two players before passing across to Lookman, who slotted a shot into the far corner.
Retegui was brought on for De Ketelaere late on and he volleyed a cross into the bottom corner to seal a fine win.
Source: BBC