CHICAGO (CBS) -- We're counting down to Sunday's Chicago Marathon.

On Friday, some of the race's top-seeded runners spoke about how they're feeling, including a former NCAA cross country champ, making his highly anticipated marathon debut.

"I get really excited about it but then I need to remember that it's my first marathon, so there's a little bit of unknown when I'm running this distance, said first-timer Conner Mantz.

The runners are ready and the course is ready too. CBS 2 spotted a lot of people snapping photos near the starting line in Grant Park. The marathon begins at 7:20 a.m. Sunday with the wheelchair division.

Runners step off at 7:30.

There are changes to the marathon course this year, including adding a stretch of Michigan Avenue in Bronzeville. Click here to see what's new for this year's race.