Benfica coach Jorge Jesus is resigned to losing star midfielder Nemanja Matic this summer.
"Of course Matic's exit worries me," Jesus told Benfica TV.
"When he came to Portugal he was on the periphery at Chelsea. We thought that he had potential. In the two years that followed we worked with him and made him the player he is today, highly coveted by the biggest clubs in the world.
"It is not easy to replace a player with the quality of Matic, but last season I was in tougher situations after the exits of Javi Garcia and Witsel.
"I wish he didn't leave, but I know that is almost impossible, given the demand there is for him."