Osasuna defender Carlos Cuellar may still move to Rangers with reports suggesting the Ibrox club have made a third bid for the player.
Cuellar impressed at Ibrox during last season's Uefa Cup tie
The 25-year-old's agent, Pedro Bravo, told BBC Scotland: "The club president knows Carlos wants to go to Rangers.
"So he will sell him if Rangers offer something closer to his buy-out fee of six million euros (£4m)."
"However, he's sold some top players already and he feels the fans will go mad if their best defender goes too."
Cuellar is known to be keen on a move to Ibrox, but the clubs have so far been unable to agree a fee.
The Spanish side - who eliminated the Glasgow club in the Uefa Cup in March - have already sold two key players, Raul Garcia and David Lopez, but hope to keep Cuellar.
However, Rangers manager Walter Smith may increase his offer for the defender following the departure of Karl Svensson to French club Caen last week.
And Bravo added: "There must be an agreement between Osasuna and Rangers for Carlos to go to Glasgow, and if there is an agreement with Rangers then we will sit down and talk.
Osasuna manager Jose Angel Ziganda, meanwhile, will seek an urgent meeting with Cuellar.
"Carlos has a deal that runs until next summer and I want to know his thoughts," he said.
"I only want players who are concentrating 100% on the team, and if they are not happy and want to leave then we must find a positive solution for everyone."
"Rangers have made offers but we have rejected them so far."