A torn ACL and meniscus turned out not to be the only health issues doctors discovered when they examined Mariano Rivera on Monday.

They also found a blood clot in his right calf, causing the closer to stay overnight in the hospital and striking fear into his heart.

"I was more concerned about the blood clot than the knee," Rivera said. "For a minute I thought, 'What else is gonna happen?'… I was scared. I never hear good things about blood clots."

Rivera, who complained of pain of stiffness in the area before learning of the blood clots, has been on blood thinners ever since. He said the clot will not delay the date of the surgery, which still has not been set because he needs to rehab the knee and get some range of motion back before going under the knife.