Matic made the move to Portugal in January 2011 as part of the deal that took David Luiz in the other direction to Chelsea, with Benfica also receiving a transfer fee of around £21m.
The Serbian midfielder was a fringe player at Stamford Bridge but has progressed rapidly over the past couple of seasons and his signature is now one of the most coveted in Europe.
Chelsea are reportedly keen to lure him back to London, but face competition from elsewhere as Real Madrid continue to follow his situation with interest.
Benfica boss Jorge Jesus concedes that the 24-year-old could be set to leave the club but insists they can cope with losing key players, like last summer when Javi Garcia joined Manchester City and Axel Witsel left for Zenit St Petersburg.
"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."