But the two drivers and their respective teams persevered to come home with top-15 finishes in Saturday’s Drive for Safety 300 NASCAR XFINITY Series race atChicagoland Speedway and clinched spots in the series’ inaugural Chase.
Sieg wound up 12th while Koch battled to a 15th-place finish in the 200-lap race.
"We're going to have to be top 15 or better each race, be on our game and make no mistakes," said Sieg, driver of the No. 39 Chevrolet for RSS Racing. "If some other people make mistakes, we can benefit from that and make it to the next round.
"You've got to race hard and get everything out of everybody; it's going to be a struggle but we're ready for it."
Sieg, 29, will enter the seven-race playoff seeded ninth, 12 points behind Saturday's race winner, top-seeded Erik Jones (Joe Gibbs Racing). Sieg is not alone – nine of the 12 drivers in the field qualified for the Chase on points, and will begin with 2,000-point total after the reset.
It's a daunting task for Sieg's group, as well as for Koch and others who have seenSprint Cup-affiliated teams dominate the competition this season.
But they'll all be racing for the same hardware come next week, and to be among the handful in that position is a win in itself.
"This is huge," Sieg said. "It's like a race within a race – the Cup affiliated teams and the smaller teams. We're one of the top two smaller car teams. This is like our little championship here. It's exciting; I'm ready to go to the next three."
For Koch, it was a stressful event at Chicagoland, in part brought on by a season spent on the Chase bubble. The vibration in the No. 11 Kaulig Racing Chevrolet only made matters worse.
The concern in his voice as the race wound down wasn't anything new.
"How about a little concern in my voice all race long?" said Koch, who called the event "the biggest XFINITY race I've ever been a part of.
"I had this little vibration that just scared me. When you're in this tight of a points battle you want everything to feel perfect and I had a vibration through my shifter; I don't know where it was. It never went away, it never got worse."
It was not the first time the issue had cropped up; the last time it did, Koch said, he failed to finish the race.
"So it just had my stomach in knots," the 31-year-old said. “Chris (Rice, crew chief) was able to use his psychology and get my head off of it and just race the race."
The XFINITY Chase format consists of seven races and three rounds, with four drivers eliminated at the conclusion of each of the first two rounds. The drivers in the Championship 4 will go to Homestead-Miami Speedway to determine the champion.
The Round of 12 will consist of stops at Kentucky, Dover and Charlotte while Kansas, Texas and Phoenix make up the Round of 8 races.
"I feel like I've been points racing all year, like I've been the guy on the bubble every single race," Koch said. “You're going to have to be smart at Kentucky and get through there with a solid finish but then I think you can go to Dover and let it all hang out."