On the last day of the summer transfer window, he stopped Mark Gaye's departure to Liverpool, and now he is ready to let him go.
Oliver Glasner, Crystal Palace manager, said that the Selhurst Park club would sell their captain in January if someone offered the asking price, reports the BBC.
The England centre-back's contract expires in the summer, and in the meantime, Manchester City have emerged as one of the main candidates to bring him in during the winter transfer window.
"I'm not naive. If a huge offer comes from City and Mark wants it, the transfer will happen," said the Austrian expert.
Palace blocked a £35m transfer to Liverpool last summer but now risk the 25-year-old leaving at the end of the season without compensation.
City's interest in Gaye grew stronger after injuries to City defenders Joško Guardiola and Ruben Dias during Sunday's draw with Chelsea.
Liverpool is reportedly still interested, as are clubs outside the Island such as Bayern Munich, Real Madrid, Barcelona, Inter and Atletico Madrid.
"If we look only at the sporting aspect, everyone at the club will say that Mark has to stay. The club president will tell you the same, but the financial situation is also important," added Glasner.
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