Alvaro Morata came off the bench to earn then score a late penalty as champions Juventus went four points clear at the top of Serie A on Sunday with a 2-0 win over hapless Inter Milan.

Days after rescuing their Champions League hopes with a 2-2 home draw with Bayern Munich, Juventus welcomed Roberto Mancini's visitors looking to steal a march on title challengers Napoli.

After a dominant first half, the hosts broke the deadlock two minutes after the restart when Leonardo Bonucci fired Inter midfielder Danilo D'Ambrosio's header past Samir Handanovic on the volley.

Morata replaced Juve striker Paulo Dybala with eight minutes remaining, and two minutes later stepped up to send Handanovic the wrong way after winning a penalty when he was chopped down in the box by Joao Miranda.

Juve's 19th win of the season leaves Massimiliano Allegri's men four points clear of Napoli, who will be hoping striker Gonzalo Higuain finds his scoring boots again for a difficult trip to fourth-placed Fiorentina on Monday.

Inter remain in fifth place at 13 points behind Juve, but their seventh loss of the campaign has all but ended their titles hopes and given hope to their direct rivals for the third and last Champions League qualifying spot.

While a reportedly ailing Mancini decided not to speak to media, Allegri was only too happy to have removed a direct rival for the league trophy.

"It wasn't easy tonight with a wet pitch and the players sliding around, but the boys did great to take control of the game and secure a precious win," said Allegri.

"We've taken one of our direct rivals for the title out of the race.

"Now, we're in a position where we can win a fifth consecutive title and that hasn't happened since 1935."

Inter sporting director Pierre Ausilio took over media duties, and seized the occasion to hit out at the team.

"The players really need to have a good look at themselves," slammed Ausilio.

"We shouldn't be letting goals in like we did the first one, but looking at our league position explains everything.

"No disrespect to Verona or Carpi, but more than losing to Juventus, we should be angry at the fact we've let smaller teams take points off us at home."

Former Inter midfielder Hernanes, handed a rare start by Allegri after a sterling performance as a second-half substitute against Bayern in midweek, announced the hostilities after just five minutes.

Taking a pass from fellow Brazilian Alex Sandro, Hernanes sidestepped his marker to hit a sweet left-foot drive that sailed over Handanovic and cannoned off the crossbar.

It took until 25 minutes for Inter to get a sniff of goal, but Sandro produced a great saving header at the back post as D'Ambrosio waited to pounce and then Giorgio Chiellini made a timely interception on Mauro Icardi to thwart the Argentine striker.

Juve spurned two chances to break the deadlock on the stroke of half-time, Paul Pogba's delivery across goal finding no takers and then Mandzukic narrowly missing the Frenchman's inviting through ball that forced Handanovic out to parry.

The first half fizzled out, but the second started with a bang when, after just two minues, Bonucci broke the deadlock.

Dybala floated in a free-kick from the right that was met by D'Ambrosio, whose header towards the back post provided the perfect assist for Bonucci to smash into the roof of the net.

"Bonucci scored a great goal, it wasn't easy," added Allegri.

Juve almost doubled their lead minutes later, Dybala's first-timer from Sandro's cross on the left trickling past the right post.

Juve's fans were up in arms when Juan Jesus chopped Dybala down from behind, and it was similar indiscipline that led to Juve's second six minutes from time.

Morata appeared to irk Miranda as they tussled for possession on the edge of the box, the Brazilian retaliating with a challenge that saw the referee point to the spot.

Morata made no mistake, sending Handanovic the wrong way to send a virtually packed stadium delirious.