New York Yankees reliever Mariano Rivera pitched one inning on Sunday, two days after undergoing tests to determine the cause of recent headaches.
On Friday, baseball's all-time saves leader had a CAT-scan and blood tests after complaining about headaches for about two weeks.
"It was severe," Rivera told The New York Post on Saturday. "When you have issues you want to make sure everything is OK. They said it seems like migraine headaches."
Rivera said he has never suffered from migraines while general manager Brian Cashman said the team would not take any chances.
"Even if there is one-half of a percent [of a problem], you want to rule it out. We weren't worried about it."
This spring, opposing batters are hitting .083 against Rivera.
The 43-year-old future Hall of Famer is retiring after this season. Last year, he pitched on 8 1/3 innings before tearing the ACL in his right knee.