Ajax are interested in signing FC Twente defender Douglas in the summer, according to coach Frank de Boer.
Star centre-back Jan Vertonghen is expected to depart Amsterdam at the end of the season, with the Belgian heavily tipped for a move to the Premier League.
Vertonghen's absence would leave a void in De Boer's backline and it is thought he is eyeing Twente's Brazilian-born Dutchman Douglas as a replacement.
The 24-year-old is out of contract in Enschede in the summer but Twente have an option to extend his deal by a further year.
De Boer told NOS: "It is correct that we are keeping tabs on Douglas as a potential replacement for Vertonghen.
"He is one of the best defenders around in the Netherlands. He is a real killer at the back and a classic defender."