Sunderland know price to sign Ondrej Celustka permanently
Celustka has impressed in the opening games of the season on-loan from the Turkish club.
As is this the case with all overseas loans, a clause has been built into the deal to convert it into a permanent switch, says the Sunderland Echo.
But Sunderland would have to pay a fee of £2.5m to activate that agreement next summer, if they want to keep the 24-year-old.
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