Yankees closer Mariano Rivera's longshot bid to get back on the mound this season has suffered a setback.

A blood clot was discovered in his right calf less than a week after he tore a ligament in his right knee.

The 42-year-old Yankee closer is on blood-thinning medication to dissolve the clot.

"I was scared because I mean I never hear good things about blood clots. I mean if there's one thing, I know that one thing, but I never hear good things about it. So I mean I was scared, definitely," Rivera said at a news conference Wednesday.

The Yankees star reliever needs to spend at least a week or two strengthening his knee before he can undergo surgery to repair the torn ligament.

He said he needed to strengthen his knee regardless of the blood clot.

The MLB's all-time leader in saves said he will come back to pitch even if it takes until next year.