Yildirim said he rang fellow Turk Turan to get his opinion on Brazilian attacking midfielder Diego, who signed for the Super Lig club in July on a three-year deal.
Diego was at Atletico for one-and-a-half seasons split across two stints, either side of time spent in the Bundesliga with Hamburg.
And Yildirim denied reports he was unhappy with Turan's assessment of Diego, claiming the Turkish winger simply provided an honest appraisal of his former team-mate.
"I called Arda and asked him his opinion [on Diego]," Yildirim said.
"He told me he was in a very good shape but that the team was playing with a system which kept him out of the starting line-ups.
"That's all Arda Turan said. We don't need to get angry with him nor to contest.
"If you [the media] claim something, you should prove it. I stand behind my own words."
