Manchester United midfielder Shinji Kagawa says he is dissatisfied with his first season in English football, despite lifting the Premier League title.
Kagawa, 24, arrived at Old Trafford last summer with a big reputation having played a key role in Dortmund's back-to-back Bundesliga triumphs.
The Japan international showed plenty of glimpses of quality throughout the season - notably with a memorable hat-trick against Norwich in March - but injuries hampered his consistency.
And after securing his third straight league title, Kagawa has promised United fans that there is plenty more to come from him.
"I was looking to produce even more results," Kagawa said. "I was injured and I felt things didn't go well easily. I had a lot of conflict, frustration and worries. In that sense, I think it has been a profound year.
"Honestly, I haven't contributed as much as I did at Dortmund. I was even injured. I still don't quite have that feeling of accomplishment. But I've managed to win three in a row. I think my career is bound to get better and better."