AC Milan and Inter Milan have sent a joint letter to the city's mayor asking to renovate or rebuild San Siro, their shared home, without council interference.
Milan and Inter, tenants at the city-owned stadium, wish to work together to bring the venue up to modern standards, and have asked the council to grant them ownership of the land, or at least a long-term lease.
Just over three years ago, Milan submitted plans to build a stadium of their own, but these were scrapped shortly before Silvio Berlusconi sold the club. Now, they are intent on staying at San Siro with Inter.
"I'm convinced we will have the best stadium in the world," Milan president Paolo Scaroni said at a news conference in Milan. "We've launched this project together with Inter and I assume the right to make a U-turn on building a new stadium of our own, going our own way, by supporting a shared stadium."
The clubs are analysing several options for renovation including removing the top tier, or even knocking San Siro down and building a new one.
"Building a new stadium is easier than renovating it," Scaroni said. "We've not submitted plans yet, but the planning is going to be complex because we're not only focusing on the stadium but the overall area.
"There are two ideas, both with their advantages and drawbacks. We're keeping both options open and will reach a decision in the coming weeks."
San Siro is only rarely full -- therefore a lower capacity is likely for the future San Siro, which has been the two clubs' shared home since 1947.
"As it stands, San Siro has a capacity of around 78,000 seats and we're imagining a lower capacity," Inter Milan's general manager Alessandro Antonello said. "The current average crowd is 60,000 and reducing the capacity does not frighten us in terms of revenue.
"Maybe we will have smaller stadium, but it will not be inferior in terms of excellence."
Since Juventus completed their stadium in 2011, Udinese have renovated Stadio Friuli and Frosinone became the latest Italian top-flight club to open a new ground in 2017.
Roma's plans to build a new stadium in the Italian capital moved a step closer to realisation earlier this week when the city mayor Virginia Raggi said she expects work to commence before the end of the year.
Last month, Bologna also unveiled their plans for a new stadium while Fiorentina have also presented a project for a new ground. Napoli are also keen on either leaving or renovating Stadio San Paolo -- one of many grounds in Italy built or renovated for the 1990 World Cup which have not undergone extensive modernisation work since.
The city of Milan is bidding to stage the 2026 winter Olympics and having a new stadium ready in time for that event could support their bid.