Tony Stewart will decide when he is ready to return to NASCAR Sprint Cup race, Brett Frood, executive vice president of Stewart-Haas Racing, said at Michigan International Speedway on Friday.

Stewart did not race at Watkins Glen the day after the sprint car he was driving struck and killed fellow driver Kevin Ward Jr. last Saturday night at Canandaigua Motorsports Park, a dirt track in New York.

He will not drive in the Pure Michigan 400 at MIS on Sunday.

"This decision (to sit out the MIS race) was Tony's," Frood said. "He's grieving. (He) made the decision he's not ready to get in the race car and will take it week by week.

"It will be up to Tony when he's ready to get back in the car."

Jeff Burton will drive Stewart's No. 14 Chevrolet at MIS.