The right-handed starter went down immediately Tuesday after being struck behind his right ear by a line shot by Tampa Bay's Manny Ramirez in the fourth inning. Oswalt was able to turn away a bit before the blow, the Philadelphia Daily News reported.
Trainers at the Port Charlotte, Fla., facility rushed to the mound but the 33-year-old hurler was able to leave the field under his own power and never lost consciousness, the newspaper said.
X-ray exams were taken as a precaution and proved negative, the team announced. Oswalt was diagnosed with a neck contusion.
The 10-year veteran finished the day allowing three runs on four hits over three-plus innings, walking none and striking out four batters.