Besiktas have emerged as favourites to sign goalkeeper David Ospina from Arsenal, Sky sources understand.
The 29-year-old Colombian international, who has two years remaining on his contract, is free to leave Arsenal following the £19m signing of Bernd Leno from Bayer Leverkusen in June.
Arsenal are understood to prefer that Ospina leaves on a permanent basis rather than on a loan deal.
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There is no rush to complete a deal as - unlike the English transfer window, which closes on Thursday - Turkish clubs are free to sign players up until August 31.
Ospina, who has been capped 90 times by Colombia, has served as Petr Cech's understudy since joining Arsenal from Nice in 2014, although he has often been the primary option in cup competitions.