The 23-year-old is said to be keen to depart Anderlecht, and is eyeing up the Premier League, although he has also been linked with a move to Atletico Madrid.
West Ham had also expressed their interest and were thought to be monitoring the midfielder, however David Moyes was not willing to cough up the £20million Anderlecht wanted back in January.
The Belgian international stands at 6ft 2ins and operates as a holding midfielder, but is also able to play at centre-back.
Palace will be aiming to wrap up the early signings ahead of the World Cup. Roy Hodgson's side seem likely to avoid the drop zone, and are six points clear of relegation in the final few matches of their campaign .