The game was a far cry from the stalemate both sides shared back on the opening weekend as Torino continued their mini revival.
The damage was done in the first half. Reginaldo cancelled out Matteo Brighi's opener, before Rolando Bianchi and Alessio Cerci gave the home side a two goal cushion. Michele Paolucci got one back late on, before Alessandro Rosina shot a penalty wide in the last minute. Siena's losing streak extends to six games.
Both sides came into the match somewhat decimated. The home side missed suspended quintet Matteo Darmian, Alessandro Gazzi, Kamil Glik, Salvatore Masiello and Giuseppe Vives. Injured trio Mario Alberto Santana, Abou Diop and Angelo Ogbonna joined them on the sidelines, while Alessandro Agostini and Alessandro Sgrigna both joined Hellas Verona in midweek.
Siena were effectively without a strikeforce, following top scorer Emanuele Calaio's loan move to Napoli and Fiorentina taking up co-ownership of Marcelo Larrondo. In addition, midfielder Gaetano D'Agostino was left out as he looks set to join Pescara and Angelo was suspended.
Torino opened the scoring on five minutes. Cerci played in Danilo D'Ambrosio, who pulled the ball back across the box for Brighi to smash home from close range.
Siena equalised with a touch of good fortune. Massimo Paci's corner evaded everyone, hitting Reginaldo's thigh and bouncing off his chest and into the net.
The lead lasted six minutes. An unmarked Bianchi headed the hosts back in front on 38 minutes, meeting Valter Birsa's pinpoint cross from six yards.
Paci wasted a couple of headers as Siena laid siege to the Torino goal with a flurry of set pieces before the break. Jean-Francois Gillet flew out to fist clear a dangerous Rosina delivery, then used his body to block Francesco Bolzoni's pull back. Gillet foiled Paci once again, tipping a third header over the bar.
Torino punished their wasteful visitors in first half stoppage time. D'Ambrosio's up field clearance was picked up by Cerci, who rounded Pegolo and slotted home into an empty net.
The visitors mounted a fight back. Nicola Belmonte and Bolzoni both missed chances, while Reginaldo controlled the ball in mid-air and volleyed over.
With 20 minutes to play, Gillet thwarted Rosina, stopping the ball going into the top corner.
For the second consecutive week, substitute Paolucci set up a tense finale, slotting home a consolation from close-range after Reginaldo teed him up with a side-footed pass.
Gillet denied Andrea Sestu's volley nestling under the bar. From the resulting corner, Brighi almost went from hero to zero when he tripped Francesco Della Rocca in the box. It was a definite penalty, but Rosina fluffed his lines against his former club and sent his spot kick well wide to let Torino off the hook.
Torino: Gillet, Caceres, Di Cesare, Rodriguez, D'Ambrosio, Birsa, (Suciu 80) Basha, Brighi, Cerci, Bianchi, Sansone (Meggiorini 80)
Siena: Pegolo, Felipe, Paci, Neto, Bolzoni, (Della Rocca 73) Valiani, (Paolucci 41) Del Grosso, Vergassola, Belmonte, (Sestu 56) Rosina, Reginaldo
Goals: Brighi 5 (T) Reginaldo 32 (S) Bianchi 38 (T) Cerci 45 +2 (T) Paolucci 75 (S)
Missed penalty: Rosina 89 (S)