The 6-foot-10 inch Durant -- Seattle's first-round pick (second overall) in this year's NBA Draft after playing just one season at the University of Texas -- suffered the injury in the fourth quarter of Tuesday night's 126-122 overtime loss to Golden State.
"He'll be all right," Sonics forward Chris Wilcox told The Seattle Times. "He said it wasn't that serious. Hopefully, it wasn't and we'll get him back before the regular season."
The 19-year-old Durant was fitted for a boot for the ankle after X-rays were negative.
"It was excruciating pain and it was hurting a lot," Durant said, "but once I was able to get up on it, the pain decreased a little bit."
Seattle plays two more pre-season contests before its regular-season opener at Denver Oct. 31.
Durant will miss both exhibition games.
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