Chelsea defender Yuri Zhirkov says his health is "much better" than last season but admits he is still suffering pain in his knees.
Zhirkov, 26, joined Chelsea from CSKA Moscow last summer for a fee believed to be in the region of £18 million, but a knee injury restricted his involvement and he did not start in the Premier League until late December.
Zhirkov was able to play regular football during Ashley Cole's absence earlier this year and made a positive contribution to the club's title success, but he has now revealed that he still suffering from the problem and could require further surgery.
"I had to miss a major part of the pre-season preparations," he told Sport Express. "After my summer holidays, I still had sharp pain in my knees and had to visit Moscow for consultations, and also to consult with a doctor from Germany in London.
"The medical procedures and exercises helped me feel much better than last year, but the pain still bothers me after matches and trainings. In general, though, my health is much better than last year.
"I've decided that one month should be enough for me to return to my peak form. If I don't manage to get rid of my problems, it will be necessary to do something about it. I'm looking optimistically at my future and I'm sure that I will shake off my injury, although I don't know when it will happen."