New York Yankees closer Mariano Rivera has a blood clot in his right calf and is on blood thinners to dissolve the clot.
The problem was discovered while he was being examined after injuring his knee during batting practice last week.
Rivera will spend at least a week or two strengthening his knee before he has surgery for a torn anterior cruciate ligament, but he says that would have been the case regardless of the blood clot.
Last week, Rivera said he was touched by the outpouring of support he received after the knee injury.
Kansas City Royals Manager Ned Yost called Rivera “one of a kind,” and Philadelphia Phillies closer Jonathan Papelbon referred to him as the “godfather” of their role.
“It's just kind of tough to put into words,” Papelbon said. “It's just tough to see your leader, your idol — it's hard to even comprehend it or talk about it.”