Following a scan, it has been confirmed that last season's MVP fractured his right foot during a recent training session - an injury which is commonly known as a 'Jones fracture'.
The 26-year-old is now expected to undergo surgery, which is likely to sideline him for around 20 NBA matches.
"After practice yesterday, Kevin made us aware of discomfort in his right foot. We proceeded to perform the necessary imagining studies to determine the cause of his discomfort. At this stage, Kevin has been diagnosed with a 'Jones fracture'," the Thunder's general manager Sam Presti said in a statement.
"Traditional treatment of this injury requires a surgical procedure and recent NBA cases have resulted in a return to play in six to eight weeks. We are in the process of collaboratively evaluating the most appropriate next steps with Kevin, his representatives, and Thunder medical personnel. Until a course of action is determined, we are unable to provide a timeline specific to Kevin's case."
OKC begin their 2014-15 campaign with a trip to Portland Trail Blazers on Wednesday, October 29.