The Italian giants had an opening bid of €60m rejected on Saturday, just hours before the two clubs met each other in the International Champions Cup in Singapore.
United quickly turned down Inter’s opening offer, which was thought to include add-ons, as they are looking to recoup the total fee of £90m that they agreed with Everton two years ago.
However, it is now claimed that Inter are being forced to consider alternative strikers after being put off by the cost of signing Lukaku.
The two names in consideration are Roma’s Edin Dzeko and Lille’s Rafael Leao, who is a highly-regarded 20-year-old Portuguese striker.
These names fit the profile that Inter general manager Beppe Marotta told Gazzetta dello Sport this week when he said he was looking for
“One striker will be an expert, the other will be a younger player with potential.”
Leao joined Lille last summer as he forced a free transfer from Sporting Lisbon after fans invaded their training ground and assaulted players.
His representative is Jorge Mendes and Portuguese-Italian sports reporter Claudia Garcia claims Rafael Leao has also just been signed up to the super-agent.
Leao scored eight goals with two assists in 24 Ligue 1 appearances last season.