According to Gianluca Di Marzio, Galatasaray's move for Martinelli would only be triggered if the club cannot get a deal for Leão over the line, with head coach Okan Buruk having made signing a marquee wide forward a priority for the summer.
Galatasaray have already opened contact over Martinelli's willingness to move to the Süper Lig, though Arsenal are not actively looking to sell the Brazilian.
Milan, though, have already knocked back an opening offer from Galatasaray for Leão worth around €30m plus €5m in bonuses, judging it well short of the roughly €50m valuation they have set for the Portugal international. The Turkish club are expected to return with an improved proposal, but Milan's stance leaves the move far from straightforward.
Any departure for Martinelli would also complicate matters at Arsenal, who would need to identify a replacement of their own before sanctioning a sale, particularly with Vinicius Jr's stay at Real Madrid looking increasingly secure after the Brazilian's contract extension this week, closing off one option the Gunners had been tracking as a long-term alternative in that position.
Leão himself has yet to indicate any appetite for a move to Turkey. The 27-year-old is said to be settled under new head coach Ruben Amorim and content with life at San Siro, leaving Galatasaray facing resistance on two fronts if they are to land their primary target this summer.
Reports in Turkey suggest Galatasaray's revised offer could take the shape of a loan with an obligation to buy worth around €40m before add-ons, still someway short of Milan's asking price but a step closer to bridging the gap between the two clubs.
The presence of Victor Osimhen at RAMS Park, a player Leão knows well from his time in Serie A, is thought to be one factor that could yet persuade the winger to take Galatasaray's interest more seriously.
AC Milan, for their part, are said to have also fielded interest in Leão from clubs in England, including a surprise enquiry from newly promoted Leeds United, underlining the scale of the market the Rossoneri believe exists for their forward even as they hold out for a fee closer to their valuation.