Douglas Costa produced an inspirational performance off the bench as Juventus came from behind to beat Bologna 3-1 at the Allianz Stadium on Saturday, meaning they will become Serie A champions again if Napoli lose to Torino on Sunday.

Massimiliano Allegri's men looked in trouble after falling 1-0 down to their visitors in the first half, but they rallied with a vengeance in the second period - half-time substitute Costa playing a starring role with two assists to ensure they head into the Coppa Italia final against AC Milan on Wednesday in high spirits.

Juve's start gave no indication they would need another comeback like they did to beat Inter last time out, as they caused Bologna's backline plenty of problems.

But a Gianluigi Buffon error coupled with a clumsy Daniele Rugani tackle allowed Simone Verdi to put Bologna ahead from the penalty spot in the 30th minute, the centre-back saved from a red card by VAR.

With Juve offering little out wide, Allegri sent Costa on from the bench at the interval and his impact was as desired, but it was a Sebastien De Maio own goal restored parity.

Costa set up two goals in six minutes just after the hour mark, finding Sami Khedira and then Paulo Dybala to seal all three points for Juve, leaving them on the brink of a seventh successive title.

There was no sign of early Bianconeri nerves as they made a strong start and nearly went ahead in the seventh minute, Gonzalo Higuain drawing a good save from Antonio Mirante after Claudio Marchisio carved the visitors defence open.

Bologna were guilty of a defensive mishap a few minutes later, as Dybala robbed De Maio just outside the area before seeing his effort deflected harmlessly over.

But Juve shot themselves in the foot after half an hour, Buffon selling Rugani short with a pass that forced the centre-back to haul the sharp Lorenzo Crisetig to the ground in the area.

Although the VAR review which concluded Rugani should not be sent off took a while, Verdi kept his cool to dispatch the spot-kick in remarkably confident fashion.

Juve failed to threaten again before the break and Allegri responded at half-time by introducing Costa on the left wing for Blaise Matuidi, with the Brazilian making a significant difference.

But the equaliser came via the opposite flank – Juan Cuadrado's curling cross calamitously flicked into the back of the net by Bologna defender De Maio.

Juve were lucky to remain on level terms just before the hour mark, however, as a cross found its way through to Emil Krafth and Buffon tipped his effort onto the post.

The hosts soon capitalised on that let-off, Costa's deep left-wing delivery finding Khedira at the back post for an easy finish.

And the Brazil international was at it again in the 69th minute, tearing up the left and playing a low cross into the area for Dybala to guide home.

It was plain sailing from there for the defending champions, as they heap the pressure back on Napoli ahead of their meeting with Torino.