Legendary marathon runner Joan Benoit Samuelson, who was slated to run the Chicago Marathon Sunday, will no longer participate in the race due to an illness, marathon officials announced Saturday.

"I was looking forward to racing once again on the streets of Chicago, but unfortunately it wasn't in the cards," Benoit Samuelson said. "While I won't be running on the roads, I will be running on the sidelines to cheer on the more than 40,000 runners tomorrow as they celebrate their stories and journeys." 

Benoit Samuelson, of Freeport, Maine, planned to run the marathon to commemorate the anniversary of her first-place victory in 1985 when she won the race with a record-breaking time of 2:21:21.

In addition to her win at the Chicago Marathon 30 years ago, Benoit Samuelson also broke a record at the Boston Marathon in 1983, won a gold medal at the first women's marathon at the Los Angeles Olympics in 1984 and made it into the Olympic Hall of Fame.