The Germany international moved back to Signal Iduna Park this summer, having spent the last six years at Rot Weiss Ahlen and Borussia Monchengladbach.
And while he is happy to have returned to the club that bred him, he is looking forward to Jurgen Klopp's side moving out of first gear as the start of the season looms.
"I'm happy about my decision to go to BVB," the midfielder told Goal.com. "But that was by no means 100 per cent. Our preparation was very hard but the workload has scaled down a bit now."
Hamburg midfielder Marcell Jansen also lauded the Bundesliga champions, who also secured the DFB-Pokal last term.
"We played against the German champions," the 26-year old stated. "They arrived with killer-confidence. They are strong on the ball and came here with a killer self-confidence."
Dortmund will start their competitive campaign on August 12, when they face Bayern Munich in the DFL Supercup.
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