Chelsea have told QPR to forget about landing Alex on the cheap after their west London rivals launched a bid to make him new manager Mark Hughes' first signing.
Blues boss Andre Villas-Boas confirmed on Thursday afternoon an offer had been made for wantaway defender Alex, with Rangers understood to be the bidding club.
Reports suggest QPR's initial offer was £3million but Chelsea are thought to be looking for more for the 29-year-old, who they claim they had no intention of selling before he submitted a transfer request.
Villas-Boas said on Thursday: "From what I know from my chief executive, there has been an approach from a Premier League club.
"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."
Rangers boss Hughes all but confirmed his intention to sign Alex at his official unveiling on Wednesday.
"There is interest in top-quality players and the player you mention is very much in that level," Hughes said.
Alex, who was banished 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 also recently admitted he would consider a return to Santos in his native Brazil.