The Turkey midfielder has revealed that he is pleased to be back at the German Champions after a tough 18 months while he denied that he was a failure during his time in Spain
The Turkey international rejoined the German champions earlier in January after 18 months away from Signal Iduna Park, and he revealed that he wanted to move back to the club so that he could enjoy his football again.
"I can only play 100 per cent when I am happy. This wasn't the case at Madrid and Liverpool," he told Ruhr Nachrichten.
"That's why I wanted to return to Dortmund.
"I just hope this story here will last for a long, long time. I know where I want to be, and I am there now."
The 24-year-old also refuted claims that his period at Santiago Bernabeu was a failure, and argued that had he not been injured, he would have become much more important to the Spanish champions.
He added: "I thought about this a lot, it cost a lot of energy. I know things would have been different if I hadn't been injured. But that was my fate.
"It might have looked like I failed. I would not see it like this. During my time at Madrid, I suffered injuries to my intra-articular ligament three times over a short period of time."