Manager Dusty Baker said Greinke is being evaluated for right arm soreness, Chandler Rome of the Houston Chronicle reports.
The 36-year-old didn't pitch during the first two games of the ALDS against the A's and Jose Urquidy was announced as the starter for Game 3, which seemed to indicate the veteran wasn't 100 percent. Baker indicated the team doesn't yet have the results from Greinke's examination, so it remains unclear when he'll next be available to take the mound.