The 22-year-old Belgium international sustained the knock in the Premier League side's 4-1 win over Malaysia XI on Sunday and had to be stretchered off.
He will now fly back to England for further tests but he was positive on Twitter that it will hopefully not be anything too serious.
De Bruyne tweeted: "Knee and ankle feeling ok for the moment. Always stay positive. Waiting for tomorrow. Then we will know more. Thanks for all the messages!"
The young midfielder then added on Monday: "Leaving to London tonight. Fully medical check-up there. Feeling ok. Hopefully a good result after the check-up."
It is poor timing for De Bruyne, who is yet to make his Premier League debut, as he hopes to earn his spot under new manager Jose Mourinho.
Chelsea will continue their build-up to the new season with a match against Indonesia All-Stars in Jakarta on Thursday.
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