NANJING, China : Matthijs de Ligt scored an own goal 10 minutes into his first Juventus start before veteran goalkeeper Gianluigi Buffon inspired them to a 4-3 penalty shootout win over Inter Milan on Wednesday.

It may only have been a friendly between the Italian arch rivals, but tempers threatened to boil over at times, especially in a feisty second half in stifling Nanjing.

The game ended 1-1 after 90 minutes, with Cristiano Ronaldo drawing Juventus level with a deflected second-half free-kick following De Ligt’s own goal.

Then the 41-year-old Buffon — more than twice De Ligt’s age — sprang to the fore in the shootout, making a triumphant return to the Serie A champions after a year with Paris Saint-Germain.

New Juventus coach Maurizio Sarri said he could “accept mistakes” —  for now.

“The feeling is that we can improve a lot, especially in the offensive part of the game,” said the former Chelsea boss.

“It is about changing the way of thinking and it is not easy to happen in a short time.”

Dutch teenager De Ligt, who joined Juventus last week from Ajax for a reported €75 million ($85 million), came on as a substitute during Sunday’s 3-2 defeat to Tottenham Hotspur in Singapore.

Sarri started the 19-year-old in the “Derby d’Italia” but the central defender got off to the worst possible beginning, directing the ball past goalkeeper Wojciech Szczesny with his knee to give Inter the lead.

De Ligt, who was one of the most coveted players in world football before his big-money move, was largely untroubled thereafter before being substituted at the break.

It was only a pre-season friendly as part of the International Champions Cup, but Antonio Conte’s Inter dealt out some rough treatment to Ronaldo.

Three times in the first half, in a match played in sweltering conditions in eastern China, the Portuguese forward was sent sprawling to the turf.

There was a flashpoint in the 51st minute when Juventus substitute Merih Demiral —  who was to score the winning penalty — lashed out while waiting for his side to take a corner.

Minutes later skipper Leonardo Bonucci talked himself into a yellow card as the referee struggled to keep control.

Man City thrash Kitchee

In Hong Kong, demonstrators chanted “Free Hong Kong” and sang a protest song as Premier League champions Manchester City hammered Kitchee 6-1 on Wednesday, underlining the political turmoil that has gripped the city.

Bayern Munich target Leroy Sane scored twice, Raheem Sterling got one and set up two more and teenagers Nabil Touaizi and Iker Pozo were also on the scoresheet as Pep Guardiola’s City outclassed the Hong Kong league side.

In the 21st minute of each half, marking an attack by a stick-wielding mob on July 21, fans struck up “Do You Hear the People Sing,” the Les Miserables song which has been adopted as a protest anthem, followed by loud chants of “Free Hong Kong!“

One banner unfurled among the 20,926-strong Hong Kong Stadium crowd said: “No China extradition, HK = police state, please save HK!!“

It follows weeks of protests in the semi-autonomous territory sparked by a government bid, since shelved, to allow extradition to mainland China for certain offenses.

On a sweltering evening, a sharp-looking Sterling rattled the bar in just the second minute and then set up the first goal for David Villa, who lifted the ball calmly over the Kitchee ‘keeper.

Sterling also provided the final pass as Sane, the subject of persistent transfer interest from Bayern Munich, drilled City’s second five minutes from half-time.

England striker Sterling made it 3-0 with a neat finish just before the break before Sane grabbed his second with a turn and shot from a tight angle after Kevin De Bruyne’s thumping strike.

Spanish teenager Touaizi came on to score City’s fifth 10 minutes from time but the biggest cheer of the night was for Kitchee’s Law Tsz-chun, who grabbed a consolation goal for the Hong Kong side.

Pozo, another 18-year-old City whizz-kid, poached their sixth goal shortly before another apparent political protest on the 90th minute, when a black-shirted pitch invader ran to the center circle and exhorted the crowd.

Football has often set the stage for political protest in Hong Kong, where fans routinely boo their own national team’s anthem, “March of the Volunteers,” which they share with mainland China.