Real Madrid are to keep hold of Casemiro despite the player's former loan club Porto initially seeking to secure his signature on a permanent basis.
The 23-year-old spent last season at the Primeira Liga runners-up, with Porto activating a release fee in his loan deal last month.
However, Real - who appointed Rafael Benitez as coach on Wednesday - have now informed Porto of their desire for Casemiro to return.
"Real Madrid has exercised the option to salvage federative rights on the player Casemiro, after FC Porto stated that his buy back clause had been activated," read a statement on Real's website.
Casemiro, who initially arrived in Madrid from Sao Paulo in 2013, was a key figure for Porto last term as he made 40 appearances in all competitions - scoring four times.
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