Roy Hodgson admits Crystal Palace face a fight to keep Michael Olise amid interest from Chelsea and Manchester City.
The Eagles have already lost Wilfried Zaha on a free transfer to Galatasaray, while four other senior players, including James McArthur and Luka Milivojevic, also left the club this summer after their contracts expired.
Jefferson Lerma, who joined on a free transfer from Bournemouth, is the only new signing so far.
Asked about the loss of Zaha, Hodgson told The Sun: 'We had two outstanding wingers who were amongst the best in the league.