The Armenia international struggled in his first season at Signal Iduna Park, having been signed by Klopp from Shakhtar Donetsk in the summer of 2014.
This season, however, the attacking midfielder has flourished under new coach Thomas Tuchel - with Klopp leaving Dortmund last May and joining Liverpool in October.
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He told Bleacher Report: "When Kloppo was here, we were playing another kind of football, more counter-attacks, more powerful, more pressing.
"When Tuchel came, we started to play a different kind of football. We try to keep the ball more, we try to pass it more and play very offensive football.
"Because of the changes I got a lot of confidence."