JOLIET, Ill. -- Chase Elliott isn't questioning whether he should have competed Saturday in the 300-mile Xfinity Series race and isn't questioning whether he'll be ready for a 400-mile race Sunday afternoon in the sweltering Chicagoland Speedway conditions.

Elliott was able to walk to an ambulance but needed two bags of fluids following the Xfinity race to be ready to qualify his NASCAR Cup Series car Saturday night.

An excessive heat warning runs through Sunday night, with temperatures expected to remain in the mid-90s with a heat index of 110-115 degrees. Temperatures in cars are reaching more than 150 degrees.

Drivers in the NASCAR Cup Series will battle similar conditions Sunday.

"Those two bags of fluids I just got, that helps a lot," Elliott said Saturday after leaving the infield medical center. "Obviously [Saturday] night it will be important to get back hydrated. Luckily, those [Cup] cars are a little bit cooler than these Xfinity cars.

"Hopefully that will help some, and I'll be ready come [Sunday] afternoon."

Chicagoland is one of select tracks running a schedule with which NASCAR Cup teams do not get on track until Saturday. They practiced earlier in the day, with qualifying scheduled after the Xfinity race.

Xfinity race winner Kyle Larson said his air conditioning unit didn't work great during the event.

"I always feel like the Xfinity race is tougher -- I don't know if the cars are any hotter inside than my Cup car," Larson said. "But I always feel fine. ... Our A/C unit in the Cup car is nicer than the Xfinity Series.

"I'll hydrate as much as I can, maybe get an IV. I'm a little scared of needles. Maybe I will get an IV and feeling better."

Elliott said while everything "pretty much" worked as far as his cooling system in the car, the race "was a rough one, for sure. One of the hotter days I ever remember."

Elliott said he doesn't regret competing in the event, in which he finished 10th for GMS Racing.

"I don't question running it," Elliott said. "That stuff happens. We sign up for this stuff. It's hot and not easy. The good news is we have places like this to come to get bags of IVs and get back going."

While some of his teammates wear shirts with systems that run cold water through the shirt, Elliott does not.

"I still don't really care for it," Elliott said. "I think there's other ways to do it and not have to go that route. We'll see."

Not all drivers seemed concerned about the heat.

"Feels like another day in North Carolina," said Paul Menard, who was eighth in the Xfinity race. "No big deal."