UEFA have banned Dinamo Zagreb's Arijan Ademi for four years after the midfielder failed a drug test after a Champions League match in September, the Croatian club said on Friday.
Ademi was tested after Dinamo hosted Arsenal on Sept. 16. Both samples came back positive, but Ademi maintained his innocence.
"I am at a loss of words to describe how terrible I feel," he said. "I am not guilty, I know that I did nothing wrong but still received a drastic punishment."
Dinamo coach Zoran Mamic said the club would appeal the decision.
"To punish a player for four years after he and the experts proved that he took a contaminated supplement is senseless," Mamic said.
"Rules are rules and one must be careful what one consumes, but this is just too much because it's obvious he didn't know what he was doing.
"We will appeal to the Court of Sports Arbitration (CAS) or whoever is in charge but right now we are totally shocked."
The decision came in the same week that club CEO Zdravko Mamic was arrested because of player transfer irregularities.