More than a week after 20-year-old race car driver Kevin Ward Jr.'s fatal accident at Canandaigua Motorsports Park, Saturday, 43-year-old NASCAR champion Tony Stewart is still in seclusion.

"It's been an emotional week for him. He's grieving," Stewart-Haas Racing executive vice president Brett Frood said of Stewart during a news conference at Michigan International Speedway.

"Any time someone is lost, especially at a racetrack, it's tragic. It was a tragic accident, and he's dealing with quite a bit of grief," Frood added.

Admitting that he and Stewart are "obviously in contact," Frood explained "Tony is surrounded right now by his closest friends and family," and "his location is of a private nature right now."

During the conference, it was also announced that veteran driver Jeff Burton will be filling in for Stewart and qualified 27th in the upcoming Pure Michigan 400, Boston Globe reported.

"My role here is to hopefully provide a little stability, give that team a chance to have the most success they can have in a very difficult situation. Hopefully I can find a way to help a healing process start," said Burton who retired from full-time racing after the 2013 season.

"Obviously it's an awkward situation for everybody. But there's a lot of people at Stewart-Haas Racing that work really hard and deserve 100 percent from me and that's what they're going to get."

Pure Michigan 400 will be the second race to be missed by Stewart after the sprint car he was driving accidentally killed Ward at a dirt track in New York on Aug. 9, according to Charlotte Observer.

Frood also revealed it was Stewart's decision to not be in the Michigan race because "he's not ready to get in a race car and will take it week by week."

On the other hand, a decision has yet to be made on when Stewart might return and who would drive his No. 14 Chevrolet while he is still in seclusion.

According to Frood, no other races have been discussed aside from Stewart's Michigan race to be filled by Burton.

"It will be up to Tony when he's ready to get back in the car. We'll talk to Tony. When he's ready to get in the car, he will be in there and we'll go from there," Frood said.

While he has three NASCAR Sprint Cup championships on his belt, Stewart was said to have kept a low profile, Sporting News has learned.

"To us, he's a regular racer," NASCAR driver Roger Campbell said of Stewart.