The Belgium international moved to the Portuguese champions in 2011 from Standard Liege but has made just 13 starts in all competitions this season.
With the 25-year-old eager to secure a place in Marc Wilmots' Belgium squad for the FIFA World Cup in Brazil, his agent Paul Stefani has revealed Defour will seek a move.
"Steven will tell his club he wants to leave because he wants to play in the World Cup," Stefani told DH.be.
Stefani also confirmed that Belgian champions Anderlect are leading the race to sign him.
However, Premier League rivals Aston Villa and Tottenham are also interested in acquiring Defour, who was linked with Premier League champions Manchester United prior to his Liege exit.
"Aston Villa? It can become real. There was interest from a few other clubs in England but to say that he may sign there tomorrow? No," Stefani added.
"Anderlecht has been the most concrete from the beginning. They always said they wanted to have Steven.
"Of course Anderlecht has a chance but Steven receives phone calls from other agents who promise him a transfer to Tottenham.
"It is normal that when you hear the name of Tottenham, we want to think."
