Nemanja Matic has confirmed his desire to re-sign for Chelsea after telling Portuguese media he has played his last game for Benfica.

The Serbia international midfielder is due to undertake a medical at Cobham while the clubs thrash out a deal that is expected to cost the London club around £22m, an eye-catching amount given they had valued Matic at around £3m when using him as a makeweight in the deal that took David Luiz from the Estádio da Luz three years ago.

Chelsea, who may yet include players in part-exchange in the transfer, hope to conclude the 25-year-old's purchase before Sunday's Premier League visit of Manchester United, with the midfielder's arrival likely to conclude their incoming business for the current mid-winter window.

"I have played my last game here," said Matic. "I want to thank all the people at the club and all the supporters. Benfica will forever be in my heart. I played here for two and a half years. I gave my best in every training session, every match, and now is the right time to leave. I want to improve, I want to go to a better league and I want to go to Chelsea, the club which I also love."

Benfica had made a concerted effort to retain Matic's services, but he had made up his mind the time was right to return to England. "The Benfica president did everything he could to get me to stay here but I have wanted to leave and insisted on leaving," added the Serbian.

"I respect the effort made to keep me at the club, everyone at Benfica has been very good to me and made me very happy, but I reiterate that I insisted on going as the time is right."

Frank Lampard is expected to be fit for the game against United on Sunday, if selected, after a hamstring injury.