TAMPA — The first headache surfaced two weeks ago and Mariano Rivera described it as more than the garden variety discomfort that two aspirin could make disappear.
“It was severe,’’ Rivera told The Post yesterday morning in a George M. Steinbrenner Field dugout.
The headaches weren’t as strong, but they didn’t go away. So Friday the Yankees sent baseball’s all-time saves leader for tests to determine the cause of the headaches.
“When you have issues you want to make sure everything is OK,’’ Rivera said of the CAT-scan and blood test.
“They said it seems like migraine headaches.’’
Rivera said doctors had not yet told him how the headaches will be treated.
Yesterday, Rivera said he felt fine and that he would pitch an inning today against the Rays at Steinbrenner Field.
According to GM Brian Cashman, the Yankees weren’t frightened by the situation.
“There are protocols and we ran through them,’’ Cashman said about sending Rivera for tests. “Even if there is one-half of a percent [of a problem], you want to rule it out. We weren’t worried about it.’’
Rivera said he had never experienced migraine headaches, but one of his sisters has had them.
Cashman may not have been overly concerned the tests would have discovered something serious, but lately tests on Yankees players haven’t produced very good results.
They are already going to start the season without Alex Rodriguez (hip), Curtis Granderson (forearm) and Mark Teixeira (wrist) for sure. Derek Jeter (ankle) is still a big question mark and Phil Hughes (back) could open the year on the DL to sharpen his control.
The 43-year-old Rivera hasn’t shown signs the headaches affected his pitching this spring. If you didn’t know he had major right knee surgery last June, it’s impossible to tell by the way he has been throwing and getting around on the mound.
Going into today’s game, Rivera has made four exhibition appearances, worked four scoreless innings, allowed a hit, fanned six and walked one. Opposing hitters are batting .083 against him. In other words, Rivera is Rivera.
If the Yankees are going to survive not having Rodriguez, Granderson, Teixeira and possibly Jeter at the beginning of the season, the defending AL East champions must pitch very well. And that means turning ninth-inning leads over to Rivera, who has 608 saves.
While some decision makers believe David Robertson has the stuff to close, he has never done it outside of a two-game audition last year that ended with a rib cage injury serious enough to land the right-hander on the DL.
David Aardsma has closing experience — 69 major league saves — but the right-hander has worked one big league game (late last season) since 2010, when he saved 31 games for the Mariners, due to Tommy John surgery.
george.king@nypost.com