With just over five minutes remaining, Giorgio Chiellini nodded a cross back to Claudio Marchisio, who blasted a strike past Siena goalkeeper Gianluca Pegolo to secure three hard-earned points. The Bianconeri's incredible unbeaten streak now stands at 46 games.
Juventus took control of the game early on, Andrea Pirlo opening the scoring with a textbook free-kick after 14 minutes. With the ball close to the box, Pirlo opted to slide the ball underneath the wall and out of the reach of the Sienna stopper. Pirlo came close to a second, but saw his second set-piece denied by the crossbar.
The teams would go into the half on level terms, however, as shaky defending allowed Emanuele Calaio to beat Juventus keeper Gianluigi Buffon with a header just before the whistle.
The Bianconeri dominated possession in the second half but were unable to turn that dominance into goals until Marchisio's late strike.
Andrea Barzagli: Solid as always, Barzagli remains the leader of this defense.
Claudio Marchisio: Deservedly got on the scoresheet with a late winner after seeing an earlier attempt denied by Pegolo.
Sebastian Giovinco: Played a vital part in both goals, winning the free-kick to set up Pirlo and delivering the cross that led to Marchisio's blast.
Paolo De Ceglie: Was exposed on multiple occasions and was responsible for Siena's equaliser. Replaced at the half.
Giorgio Chiellini: Not the greatest of performances, was booked early and nearly scored an own goal. Redeemed himself by setting up Marchisio's late winner.
Arturo Vidal: Too sloppy in possession, the Chilean couldn't find his groove in the first half. Elevated his play after the break.
Next, Juventus will host co-leaders Napoli after the international break.