The 35 year-old defender's deal expires at the end of this month.
Kroos said: "I don't know how things are going with the club, I think he has 20 more days on his contract.
"We don't have to talk about the importance Sergio has for Real Madrid. I can only say that I have enjoyed a lot with him in these eight years and I hope to have many more years with him.
"He has always been a great teammate and a great captain, he has been the best captain I have ever had in my career."
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