CHARLOTTE, N.C. – Tony Stewart, a three-time NASCAR champion, underwent a second surgery on his broken right leg Thursday in North Carolina and remains hospitalized under observation.

The surgery was to insert a metal rod inside the tibia, and Stewart-Haas Racing said a specialist pressed the tibia to its correct position.

Stewart broke both the tibia and fibula in his right leg Monday night in a sprint car race in Iowa. He underwent a first surgery in Iowa following the accident to clean and stabilize the injury.

Stewart is out indefinitely and Max Papis will drive his No. 14 Chevrolet this weekend at Watkins Glen International, where Stewart is a five-time winner. It will bring Stewart’s streak of 521 consecutive Cup starts to an end.

Stewart-Haas Racing hasn’t named an interim driver for beyond this weekend, and said no discharge date has been decided for the 42-year-old driver/owner.

Stewart was leading with five laps remaining Monday at Southern Iowa Speedway when a lapped car spun in front of him, causing Stewart to hit that car and flip several times. He was taken from the track by ambulance.

It was his third sprint car accident over the last month, but his passion for grassroots racing remaines strong. He bristled just last week at Pocono Raceway when asked why he continued to put his day job at risk for his hobby.

“We all know Tony loves to do those races. We know that that’s his golf game, that’s his hunting, his fishing, all the things that the rest of us do,” said Greg Zipadelli, the competition director at SHR. “I think it makes him better at what he does here, but it obviously leaves the door open for a situation that we’re in now. I think that as many races as he’s run in the past, we’re probably lucky that this is the first time we’re dealing with this.

“We’ll do our best at Stewart-Haas to put pieces together and sit down and evaluate it. That doesn’t mean anything other than we will talk about it.”

Stewart was 11th in the Sprint Cup standings with five races to go before the Chase for the championship.