Henrikh Mkhitaryan has admitted that he has yet to replicate the form that earned him a transfer from Shakhtar Donetsk to Borussia Dortmund as he feels he has not been good enough in the first half of the season.
The attacking midfielder, 24, joined BVB in a deal worth £23 million (€27.5m), but has netted just three goals in 15 Bundesliga appearances so far after scoring an impressive 25 league goals for the Ukrainian champions last term.
"I think that I have not yet shown what I can do since I moved to Borussia Dortmund. I still have room for improvement," the Armenia international told Kicker.
"The positive thing for me is that I got plenty of chances and created some myself, too. I simply did not do enough with them, though.
"But I am confident that I will do better after the winter break than in the first half of the season. I am very critical of myself and I know that I can do better."
Dortmund resume Bundesliga action at home against Augsburg on January 25. Jurgen Klopp's men currently sit fourth in the table with 32 points from 17 games.