Duff had been set to fly to a training camp in Washington with the rest of his team-mates when the call came from Stamford Bridge. He was in London today for contract talks with Chelsea chief executive Trevor Birch.
Souness added: "When we arrived at the airport yesterday morning and checked in, Damien checked his bags through.
"Unfortunately for us, Chelsea have made an offer which triggers the clause in his contract that enables him to speak to them.
"It's going to be a difficult decision for Damien and I can understand it if he chooses to go to Chelsea because right now they are the big team in the world in terms of spending money.
"I'm sure he'll be offered a great deal of money to go there, but we still hope he'll be with us this year."
Duff can expect to double his £35,000-aweek wages should he decide to join Chelsea.
