Chelsea are determined Brazilian defender Alex won't leave in a cut price deal as west London rivals QPR try to make him the first signing of the Mark Hughes era at Loftus Road.
Andre Villas-Boas, the Chelsea manager, confirmed Thursday an offer had been made for Alex, with QPR understood to be the interested club.
It has been reported that QPR made an initial £3 million ($4.6 million) offer for Alex but Chelsea are understood to want more for the 29-year-old.
"From what I know from my chief executive, there has been an approach from a Premier League club," Villas-Boas said.
"We have respected Alex's transfer request so the market's open for him.
"We're just trying to reach the level of proposal we think is good for the player. Nothing has happened up to now, but we'll listen to all offers.
"We'll present anything to the player.
"He has to make a decision. He has generated interest from a lot of clubs."
Hughes, appointed in succession to the sacked Neil Warnock, said Wednesday of Alex: "There is interest in top-quality players and the player you mention is very much in that level.
Alex, dropped from Chelsea's first-team squad along with Nicolas Anelka after both submitted transfer requests, has previously been linked with Juventus and Paris St Germain.
He has also said he would consider a return to Santos in his native Brazil.