Basel took revenge on Paulo Sousa, as Fiorentina fumbled a lead to lose 2-1 at home with Gonzalo Rodriguez sent off.
Matias Vecino was originally named in the starting XI, but pulled out during the warm-up and made way for Borja Valero. Jakub Blaszczykowski received his full debut for the Viola and Paulo Sousa was reunited with the club he left this summer.
It took just four minutes to break through in controversial fashion, as Nikola Kalinic appeared to handle when he took advantage of a defensive mix-up, but the referee allowed the goal.
Michael Lang drilled just wide and a Mati Fernandez curler was palmed away, while Luigi Sepe had his gloves stung by Breel Embolo from a tight angle.
Basel increasingly took the initiative and Sousa shouted from the touchline that his team was too timid. Facundo Roncaglia was perhaps too rough in his manhandling of Embolo, fortunate the referee didnít spot it in the penalty area.
Josip Ilicic picked up an injury and made way for Khouma Babacar at the break. The substitute immediately created a great chance on the counter for Blaszczykowski, who went round the goalkeeper, but the angle was too narrow and he could only thump the outside of the post.
Basel had the ball in the back of the net after 53 minutes, but Marc Janko had strayed offside.
Babacar had a shot charged down in the box and Kalinicís acrobatic overhead kick was off target, but Gonzalo Rodriguez got himself sent off for a dangerous foul on Embolo to stop a counter-attack. It was a straight red for the Argentine.
Moments later, Astori had to come off, as the dizziness from an earlier knock to the head proved too much, so Marcos Alonso and Nenad Tomovic had to become their centre-back pairing.
It wasnít an ideal situation and Basel got their deserved equaliser, as Luigi Sepe didnít get a strong enough hand to Birkir Bjarnasonís finish and it bounced in off the upright. Bjarnason is no stranger to playing in Italy, as he spent several years at Pescara.
Basel kept pushing and 10-man Fiorentina capitulated, as Egyptian international Mohamed Elneny unleashed a rocket from over 20 metres that flashed into the far top corner. This time there was little Sepe could do.
The Viola had penalty appeals for an apparent trip on Kalinic waved away, but ultimately didnít do enough to put this game to bed.