Aurelien Tchouameni has become Real Madrid's fourth most expensive signing ever.
Real announced on Saturday that the 22-year-old midfielder is joining from AS Monaco on a six-year contract.
According to Marca, Real will pay Monaco a transfer fee of €80 million for Tchouameni.
Real have only paid more than €80m to buy a player three times in their 120-year history.
Based on the transfer fees reported by Marca, Gareth Bale remains Real's all-time record signing, having arrived for €101m from Tottenham in 2013.
Real paid Chelsea €100m for Eden Hazard in 2019, a decade after splashing out €96m to take Cristiano Ronaldo from Manchester United.
Monaco could eventually earn as much as €100m from the sale of Tchouameni, depending on various performance-related add-ons.
Tchouameni played 35 Ligue 1 appearances for Monaco last season and made more interceptions (101) than any other player in France's top division.
He also made 86 tackles - the fourth-highest total in Ligue 1 last season.
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