Updated

Stewart-Haas Racing does not know how many races Tony Stewart will miss with a broken right leg he sustained in a sprint car race in Iowa.

Competition director Greg Zipadelli says Stewart dodged so many close-calls over the years, "everybody around us didn't think Superman could get hurt."

The three-time NASCAR champion remains in an Iowa hospital recovering from surgery to stabilize and clean a Grade 2 break to his tibia and fibula in his right leg. He broke both bones when his sprint car flipped while leading late in a race Monday night.

Stewart's streak of 521 consecutive NASCAR starts will end Sunday at Watkins Glen.