The Serb joined Sporting on-loan last week to be reunited with his former Benfica coach Jorge Jesus.
"I came to work with Jorge Jesus, I'm proud to be here again," he began.
"I came for him, the President, the ambitions of the club .. . for me it is important."
Markovic added: "I came to be champion.
"I am happy to be here and I hope they are happy for me. I hope that together we are champions."