The South Korea international striker said: "First of all, I have not had the chances and I have had too much pressure on me.

"Firstly, I am very annoyed that the media evaluates me before the manager does. I will do my best to make sure the memory of me to Middlesbrough fans is one that I am a passionate player.

"This league is very tough and fast, much more than Korea. I would be very difficult to pass defenders and make a goal."

Lee's contract expires at the end of the season, when he will be free to leave for nothing.