Defour's representative, Paul Stefani, confirmed his player is a target for Lambert.
He said: "Aston Villa have let it be known that they are interested in Defour.
"It is not yet concrete, and it is the same story for other clubs that I can't name.
"Steven is certainly open to joining an attractive club on condition that they offer him more playing time than he has at present.
"He's not unhappy at Porto but he needs to be playing regularly with an eye on the World Cup."
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