The 27-year-old Belgium international has endured a dismal season in front of goal, registering just one in 16 Premier League appearances as Palace struggle near the foot of the table.
Roy Hodgson’s patience with his key striker has worn thin and the Eagles are set to bring in two new strikers to help with their fight for survival.
The club expects to complete the signing of Diafra Sakho, 28, from West Ham in the next 24 hours. After failing to force a move to Rennes through last summer, Sakho was expected to return to France this winter so a move across London is a surprise.
Once that deal is concluded, Everton stiker Oumar Niasse is next on Hodgson’s shopping list. The signing of Cenk Tosun, 26, from Besiktas last week makes for a crowded Toffees squad with Niasse likely to be the biggest loser.
The Senegal international has four goals in 17 mainly substitute Premier League appearances.
A desperate attempt to sign Niasse on deadline day last August failed and Palace are returning to Goodison Park with an improved offer, expected to be in the region of £13m.
Brighton are also monitoring Niasse’s situation.