Napoli's injury concerns deepened in the second half when David Neres was seen limping off. The stoppage sparked a brief flashpoint between the two sides.
The 21-year-old Alejandro Garnacho's sale value is the fourth largest for a United player after Cristiano Ronaldo, Romelu Lukaku and Angel di Maria.
Napoli begin their title defence at Sassuolo on Saturday.
Regulations in Milan, which is in one of Italy's Yellow Zones, include a curfew between 2200 and 0500 with breaches resulting in fines.
Wing back Thomas Meunier also trained individually as he continues his recovery from a cheekbone fracture. He played 20 minutes in Friday's friendly loss to Egypt in Kuwait City.
Asked whether he will make his debut against Arsenal in the Premier League on Sunday, the 28-year-old said that he has been training throughout the pre-season and "feels good".
The 28-year-old's move from Serie A to the Champions League holders is expected to be 97.5 million pounds ($135.26 million).
Napoli celebrated their second Italian title in three years -- and fourth overall -- after a thrilling battle with Inter whose 2-0 win at Como following goals from Stefan de Vrij and Joaquin Correa left them one point adrift of their rivals.
British media reported that the fee for the 24-year-old would be around 75 million pounds ($96.68 million), making him the club's second most expensive signing after last year's world record deal for French midfielder Paul Pogba.
Tracking the key moves this week in the European transfer market
Romelu Lukaku's 50th league goal for Everton put them on the way to a deserved 2-0 victory over West Ham United on Sunday, ending a run of four league games without a win. It kept the Merseysiders sixth in the Premier League and West Ham in the bottom five.
Lukaku used his goal after 10 minutes in St Petersburg to send a message of support to Eriksen, who dropped to the ground during Denmark's opening Euro 2020 game against Finland in Copenhagen and was given CPR on the pitch earlier in the day.
A summary of Monday's action in LaLiga and Serie A.
Belgium soccer player Romelu Lukaku, who is close to joining English Premier League club Manchester United, was arrested in southern California and issued a citation after failing to heed noise warnings, Beverly Hills police said on Saturday.
Despite being without key performer Kevin De Bruyne, world number one ranked Belgium were rarely in trouble against a Russia side that struggled to impose themselves.
'Oh, I need competition. When someone says he's better than me, I want to transcend him. Ronaldo wants to be the best at everything, (France striker Kylian) Mbappe also wants to win everything.'
"That is why we should see this match (against Egypt) mainly as a wake-up call. It was also useful in giving some players much-needed minutes."
Belgium's creativity and power proved too much for World Cup debutants Panama as the Group G favourites overcame the heroics of goalkeeper Jaime Penedo and a massed defence to run out 3-0 winners on Monday.
The Chelsea playmaker gave Lukaku a piece of his mind in Sochi on Monday after Belgium had huffed and puffed but failed to blow Panama's modest defensive fortress down before the interval.
The Belgian international has scored 13 league goals this season, four in the Champions League and four in the FA Cup, but has been criticised for not being effective against the bigger teams in England.
The win put United back in second place in the Premier League, still 13 points behind neighbours Manchester City, while Chelsea drop below Tottenham into fifth place.
Manager Roberto Martinez described Romelu Lukaku as the perfect striker for Everton after the Belgian bagged his 19th goal of the season to secure a 2-1 win over Manchester City on Wednesday.
Everton's Romelu Lukaku has described himself as one of the most gifted strikers in world football after scoring 25 goals in all competitions for his Premier League club last season. Despite his form in front of goal Everton finished 11th and sacked manager Roberto Martinez, although Lukaku still rates the season as his finest in terms of individual achievement. "I'm among the best. That's good. Personally I am happy," Lukaku said in an interview with the June edition of World Soccer magazine. "I did expect to produce a season of this calibre." The 23-year-old is part of Belgium's squad for this month's European Championship in France, where his team play Italy, Ireland and Sweden in Group E.
Sacked Italy manager Luciano Spalletti bowed out with a victory after his side laboured to an uninspired 2-0 home win over Moldova in their World Cup qualification match on Monday.
Manchester United midfielder Paul Pogba played a "big role" in Romelu Lukaku's decision to join the Premier League giants from Everton, the Belgian striker has said.
Manchester United striker Romelu Lukaku was quick to grab the ball when his team were awarded a penalty in the 78th minute of their Champions League game against Benfica.
Everton's Romelu Lukaku ended his longest goal drought in English football with an 11-minute hat-trick to power the visitors to an emphatic 3-0 win over Sunderland on Monday and third place in the Premier League table.
Defending champions Inter Milan secured a 2-1 home win against Udinese in Serie A on Sunday with first-half goals from Marko Arnautovic and Davide Frattesi.
Photograph of the World Cup game between Belguim and USA
Ukraine came from behind to beat visitors Belgium 3-1 in the first leg of their Nations League playoff on Thursday
Images from Sunday's action in LaLiga and Serie A.
Mourinho takes a veiled jibe at Lukaku
Napoli forward Lukaku, who has battled to regain match fitness after joining the club in late August, delivered an impressive performance with one goal and two assists.
A stunning first-half performance by striker Romelu Lukaku guided Everton to a 3-2 home victory over Newcastle on Monday to lift his side to fourth and maintain the Premier League's only unbeaten record.
British media reported that the fee for the 24-year-old would be around 75 million pounds ($96.68 million), making him the club's second most expensive signing after last year's world record deal for French midfielder Paul Pogba.
Images from the Euro 2024 Round of 16 match between France and Belgium, at Dusseldorf Arena, Dusseldorf, Germany, on Monday.
IMAGES from the European Qualifiers for the 2026 FIFA World Cup.
Belgium will have no complaints about the first VAR decision to disallow a goal, but cancelling out a second strike from Romelu Lukaku, which denied them a late equaliser against Slovakia at Euro 2024 on Monday, is the tournament's first controversy.
A Romelu Lukaku hat-trick in a 4-1 win for Everton at Young Boys and a thrilling 3-3 draw between Celtic and Inter Milan.
In-form striker Romelu Lukaku said he chose to join Everton on loan for the season from Chelsea because he needed to play regularly and not because he was not wanted at Stamford Bridge.