The Cavs fought back with a 16-to-2 run in the fourth quarter to take the lead, but faded late in a 95-86 loss to Oklahoma City at Quicken Loans Arena.
It was the sixth straight win for the Thunder.
Cleveland got 15 points from Collin Sexton and 15 rebounds from Tristan Thompson.
The Cavs fell to 1-and-10. They play the Bulls Saturday in Chicago.