Coutinho is wanted by the Spanish clubs but the Reds are refusing to sell.
Liverpool have turned down bids of £72m and £90m this summer - leading to the player putting in a transfer request last week.
And Saunders thinks the writing has been on the wall for a while.
“As soon as the phone call came in from Barcelona I thought ‘he’s gone’,” he said on BT Sport.
“It’s very difficult to stop a player.
“There’s probably only two clubs he’s leave Liverpool for - Barcelona and Real Madrid.
“One of them’s come knocking and I think the minute that call happened, he’s gone.”
Saunders thinks Liverpool are now locked in a battle with Barcelona over a fee for Coutinho.
He added: “Apparently Coutinho has asked for a transfer.
“There’s a game of poker going on between the clubs.
“And Liverpool will get as much money as they can, right at the end of the window.”
Liverpool have a nervous wait until 11pm on August 31 if they want to keep Coutinho on board.
