Calhanoglu, 20, could quit HSV at the end of the season should they fail to avoid relegation.
"We have accepted an offer from Hamburg to his contract to 2018. Yet, right now there are ten different clubs that are interested in Hakan - and Atleti are one of them," said Huseyin Calhanoglu to AS.
"Real Madrid have also spoken to my son's representative, Bektas Demirtas. But we all have to think about things this summer.
"Barcelona? No, there has not been anything with them."
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