Lazio president Claudio Lotito says he tried to keep hold of Sergej Milinkovic-Savic.
The Serbia midfielder has joined Al-Hilal in the past week.
Lotito told Il Corriere dello Sport: “I had offered Milinkovic-Savic a contract extension, but his agent said he had received a €40m proposal from a Saudi club, €18m after taxes.
“The player wanted something new but the first offer for Lazio was €15m. I told them that €15m or €0m was the same for me and that he would have run a lot around the pitch with that fee. So €15m became €30m and then €40m."