The Spain international is on his way back after a two-month absence due to injury, yet feels it could be a while before he's 100 per cent again
Martinez underwent groin surgery back in September, but recently returned to match action again after a two-month absence.
"I am optimistic that I will soon be fit again. It's impossible to be back at my usual best right away, though," the Spaniard told TZ.
"I underwent surgery and was unable to play for a while. I will need time. I am already feeling a lot better than I had expected. I need a lot of training now.
"Things are going well, as far as that is possible after a two-month spell on the sidelines. I want to regain peak fitness again as soon as possible."
The 25-year-old has made six appearances in all competitions so far this campaign, scoring once in the process.