It took Romelu Lukaku just 82 seconds to mark his return to Inter Milan with a goal.

But it was Denzel Dumfries who decided the game with a stoppage-time winner to see Inter snatch a 2-1 victory at newly-promoted Lecce on Saturday, just as the Nerazzurri appeared to be heading for a surprise draw.

AC Milan also got off to a winning start as they opened their defence of the league title with a 4-2 triumph over Udinese - albeit with the help of a controversial penalty.

Inter brought back Lukaku on loan this offseason, a year after he left to join Chelsea shortly after firing the Nerazzurri to the Serie A title.

It took the Belgium forward less than two minutes to reopen his Inter account. Federico Dimarco floated in a cross from the left and Matteo Darmian nodded it back across goal for Lukaku to head in from close range.

The home side levelled shortly after the break when Federico Di Francesco fed Assan Ceesay for an angled drive into the far bottom corner.

Lecce almost took a surprise lead on the hour mark but Inter goalkeeper Samir Handanovic did well to parry Kristijan Bistrovic's fierce free kick.

It was all Inter after that. Dumfries saw a header come off the post, while Lukaku had a goal ruled out for a foul in the buildup.

Lecce goalkeeper Wladimiro Falcone also pulled off a number of impressive saves, including denying Lukaku late on.

But Falcone was let down by his defenders in the fifth minute of stoppage time as they failed to mark Dumfries and he chested the ball in from point-blank range.

It took less than 10 minutes of the Serie A season for the first refereeing controversy to arrive.

Milan were trailing when captain Davide Calabria collided with opposing defender Brandon Soppy as both went for the ball in the penalty area.

After a lengthy pause while he reviewed the incident on the pitchside monitor, referee Livio Marinelli awarded a penalty to Milan - much to the outrage of the visiting team.

Theo Hernandez converted the penalty and Ante Rebic volleyed Milan in front shortly afterwards.

Udinese were one of the only teams - along with Juventus - Milan had failed to beat in their title-winning campaign.

And a sold-out San Siro was silenced with less than two minutes on the clock when Rodrigo Becao headed in a corner to give Udinese a shock lead.

Although Milan swiftly turned things around, they found themselves pegged back at the break when Roberto Pereyra floated in a cross from the right and Adam Masina got away from his marker for a diving header on halftime.

Milan restored their lead just 30 seconds after the interval as two Udinese defenders got into a tangle as they tried to deal with Hernandez's cross, allowing Brahim Diaz to tap in.

Diaz also had a hand in Milan's fourth as he muscled his way along the byline before rolling the ball across for Rebic to fire into the top left corner.

Silvio Berlusconi's return to Serie A ended in defeat as his newly-promoted Monza side lost 2-1 at home to Torino.

Berlusconi had owned Milan for 31 years before selling in 2017. The former Italy premier bought Monza the following year.

Meanwhile, substitute Ademola Lookman scored on his debut to help Atalanta win 2-0 at Sampdoria. Lookman's goal came in stoppage time after Samp had hit the woodwork twice.