The Italian club's proposal is for a loan with an option to buy, but RB Leipzig would prefer a permanent sale or, at minimum, a loan with a mandatory purchase clause, giving them the best chance of recouping their outlay on a player who has yet to justify a hefty transfer fee.
Harder joined RB Leipzig from Sporting Lisbon just a year ago for €24million, arriving with considerable expectation after a prolific spell in Portugal, but he managed only three goals in 920 league minutes during his debut Bundesliga campaign.
Leeds United have also opened contact over a potential move, while Galatasaray remain keen as well, setting up a genuine three-way scramble for the 21-year-old's signature before the transfer window closes.
Leipzig would not stand in Harder's way should an acceptable offer arrive, though their clear preference remains an immediate sale rather than a temporary arrangement that defers the financial return.
The club's stance is complicated by the striker's underwhelming output relative to his fee, a mismatch that has left Leipzig needing to balance a swift resolution against the risk of accepting a discounted structure.
New head coach Martín Demichelis has so far preferred alternatives to Harder up front, with the Dane largely restricted to substitute appearances since the start of pre-season, though he did come off the bench to score in Leipzig's 6-0 DFB Pokal win over Eintracht Trier at the weekend — a reminder of the raw ability that persuaded Leipzig to make such a significant investment in him only twelve months ago.
Whichever club ultimately wins the race for his signature will be gambling on a talented young forward rediscovering the form that made him one of Portuguese football's most coveted strikers before his move to Germany.