HAMPTON, Ga. -- Tony Stewart took his seat on the podium -- unshaven, his eyes glassy -- and unfolded a sheet of paper. His voice quivered as he read, pausing to maintain his composure as he described the death of a driver he hit as "one of the toughest tragedies I've ever had to deal with."

This was a far cry from the brash driver known around the track as "Smoke."

Ninety minutes later, he climbed into his No. 14 car and sped toward the high-banked oval at Atlanta Motor Speedway, drawing a cheer from the crowd gathered around his garage. He quickly got up to speed, turning laps of nearly 190 mph, a racer back in his element.

Ready or not, Stewart is back on the track.

Heartbroken but eager to heal, Stewart rejoined the race for the NASCAR Sprint Cup championship surrounded by those he considers a second family -- his team, his crew, his rivals. He missed the last three races, going into seclusion after the sprint car he was driving struck and killed 20-year-old Kevin Ward Jr., who had stepped on the track to confront him during a race.

He'll get back to work as an investigation continues in upstate New York. Authorities said Friday that the probe into the cause of the crash will last at least another two weeks. No decision has been made about whether Stewart will face charges.

"This is something that will definitely affect my life forever," Stewart said. "This is a sadness and a pain I hope no one has to experience in their life. That being said, I know that the pain and mourning that Kevin Ward's family and friends are experiencing is something that I can't possibly imagine."

He mentioned Ward's parents and three sisters by name, saying he wanted them "to know that every day I'm thinking about them and praying for them."

Stewart took no questions about Ward's death because of the ongoing investigation, but said he wasn't sure if he had the emotional strength to answer them anyway. But his timid, halting delivery presented a much different side to a racer whose infamous temper has sparked clashes with the media and fellow drivers.

It was business as usual when Stewart switched to his racing suit. He signed autographs. He talked with his crew about the car's setup. He chatted up Kurt Busch.

During a 90-minute practice, Stewart posted a top lap of 189.642 mph -- 10th-fastest among the 44 drivers attempting to qualify, quickly stamping himself as a contender in Sunday night's race.

If Stewart should win this event, or next week's race at Richmond, he would qualify for the Chase for the Sprint Cup championship. While NASCAR requires its drivers to compete in every event to make the playoff, Stewart was granted a waiver that is normally applied to a driver who misses a race for medical reasons.

Mike Helton, president of the governing body, said NASCAR made the decision after consulting with third-party experts who "were relevant under these circumstances." He would not elaborate.

"We want to join everybody in racing in welcoming Tony back," Helton said. "He's a great asset to NASCAR. He's a great champion, a great participant in our sport."

There was no word from Ward's family on Stewart's return. A woman who answered Friday at the home of Kevin Ward Sr. said the family would not be commenting.

During an Aug. 9 sprint-car event in upstate New York, Stewart and Ward's cars bumped while racing into a turn, sending Ward's car spinning. Ward climbed from his wrecked machine and wandered onto a darkened track in a black racing suit, wanting to make his displeasure known to the three-time NASCAR champion.

One car appeared to swerve to avoid Ward, but he was struck by the back right tire of Stewart's car.

The 43-year-old Stewart pulled out of the race at nearby Watkins Glen the morning after Ward was killed, and then skipped events at Michigan and Bristol.

"I've taken the last couple of weeks off out of respect for Kevin and his family and also to cope with the accident in my own way," he said. "It's given me the time to think about life and how easy it is to take it for granted. I miss my team, my teammates and I miss being back in the race car, and I think being back in the car this week with my racing family will help me get through this difficult time."

Stewart was set to be back on the track Friday evening for qualifying. Driver Denny Hamlin said it was all good therapy.

"From my standpoint, getting in a race car always makes whatever is going on outside in your life a little bit better," Hamlin said.

Asked if it was fair to make Stewart eligible for the Chase, Hamlin wavered a bit.

"It's a very vague thing," he said. "It's tough to say what's considered medical and not."

Stewart-Haas Racing executive vice-president Brett Frood said the driver sent flowers and a card to Ward's family around the time of the funeral. He hopes to meet with them at some point.

"He's been very respectful of them and their time to grieve," Frood said. "It's important for Tony to spend time with the family. I do think that will happen at the appropriate time."

Stewart said he knows there are plenty of questions surrounding Ward's death. Many of those have focused on whether he was trying to frighten a young driver who had the nerve to challenge him over a racing crash. But he emphasized that the best way for him to heal was to put on his helmet.

"Tony is ready to be in the race car," Frood said. "He wouldn't be here if he wasn't."