FLORENCE - Inter produced a swashbuckling second-half display to come from a goal down and put Fiorentina to the sword at the Franchi.
The hosts took a deserved lead through Riccardo Sottil but a different Inter emerged after the restart and flipped the game on its head with two goals in as many minutes by Matteo Darmian and Edin Dzeko. Ivan Perisic then put the gloss on the win with a late third to ensure the Nerazzurri stay top.
The Viola came racing out the blocks and inside two minutes Samir Handanovic had to make his first save of the night – a feline dive at the feet of Nico Gonzalez.
In the 10th minute the keeper was again called into action to keep out Dusan Vlahovic's fierce effort.
The Viola waves continued and Cristiano Biraghi was the next to see his shot saved before another former Nerazzurri player Alfred Duncan lashed over.
Vincenzo Italiano had his side enacting a ferocious pressing game and Inter were struggling to put moves together.
A goal for the hosts looked in the air and it duly came on 23 minutes: Gonzalez sprinted away down the left and steered a low delivery towards the back post, where the onrushing Sottil was on hand to turn home.
Inter tried to bounce back, with Perisic looking particularly dangerous on the flank. The first chance came on the half-hour mark when Hakan Calhanoglu's free kick was saved by Bartlomiej Dragowski.
The Nerazzurri then had the ball in the net – technically speaking it was Matija Nastasic who put it in his own net – but Perisic was offside, so they went in at the interval a goal down.
Simone Inzaghi's men re-emerged looking a different proposition but before long the coach was lining up his first substitution, with Denzel Dumfries set to come on and Darmian ready to make way. Then fate stepped in.
Before the change could be made Darmian had finished off a flowing first-time move, exchanging passes with Nicolo Barella and angling home the equaliser.
Three minutes later the comeback was complete: Dzeko climbed highest to connect with Calhanoglu's corner and head home our second.
The double whammy took the wind out of Fiorentina's sails and the Nerazzurri came into the ascendancy. Inzaghi brought on more fresh legs and Inter controlled the game, with Barella and Marcelo Brozovic dictating things from midfield.
The hosts shot themselves in the foot 11 minutes from time when Nico Gonzalez got himself sent off after picking up two yellow cards for overdoing it with his protests.
Interi seized the opportunity to put the game to bed once and for all with a textbook counter-attacking goal, substitutes Matias Vecino and Roberto Gagliardini providing the foil for Perisic to make it 3-1.
The victory – our 1,500th in Serie A – consolidates Inter's place at the top of the table, with 13 points from five matches, sending out a message to the rest of the league in the process.
Fiorentina 1-3 Inter (HT 1-0)
Scorers: Sottil 23 (F), Darmian 52 (I), Dzeko 55 (I), Perisic 87 (I).
FIORENTINA (4-3-3): 69 Dragowski; 24 Benassi (29 Odriozola, 66), 4 Milenkovic, 55 Nastasic, 3 Biraghi; 5 Bonaventura (91 Kokorin, 84), 32 Duncan (7 Callejon, 84),18 Torreira (34 Amrabat, 66); 33 Sottil (8 Saponara, 74), 9 Vlahovic, 22 Gonzalez.
Subs not used: 1 Terracciano, 25 Rosati, 2 Martinez Quarta, 14 Maleh, 17 Terzic, 42 Bianco, 98 Igor.
Coach: Vincenzo Italiano.
INTER (3-5-2): 1 Handanovic; 37 Skriniar, 6 De Vrij, 95 Bastoni; 36 Darmian (2 Dumfries, 66), 23 Barella (8 Vecino, 70), 77 Brozovic, 20 Calhanoglu (5 Gagliardini 84'), 14 Perisic; 9 Dzeko (7 Sanchez, 70), 10 Lautaro (32 Dimarco, 84).
Subs not used: 21 Cordaz, 97 Radu, 11 Kolarov, 13 Ranocchia, 33 D'Ambrosio, 38 Sangalli, 48 Satriano.
Coach: Simone Inzaghi.
Assistants: Costanzo, Passeri.
Fourth official: Zufferli.
VAR assistant: Carbone.
Booked: Skriniar (I), Darmian (I), Calhanoglu (I).
Sent off: Nico Gonzalez 79 (F).
Added time: 1+3 minutes.