A decision by the video assistant referee (VAR) to overturn a SPAL goal and give a penalty to Fiorentina was pivotal as the Viola went on to secure a 4-1 away win at the Stadio Paolo Mazza on Sunday.
The score was tied at 1-1 with 13 minutes remaining thanks to first half goals from SPAL striker Andrea Petagna and Fiorentina's Edmilson Fernandes, when the home side thought they had taken the lead through Mattia Valoti from a counterattack.
However, a VAR review led to referee Luca Pairetto viewing an incident in the opposite penalty area and decided to disallow SPAL's goal and award Fiorentina a penalty for a trip on Federico Chiesa in the build-up. Jordan Veretout duly converted the spot kick.
Giovanni Simeone and Gerson then added further strikes for Fiorentina to give them a flattering win and move them into eighth place on 35 points, although Torino and Sampdoria have the chance to overtake them later in the day.
SPAL, meanwhile, remain in 15th place on 22 points, four points clear of the relegation zone.