Chastain and the entire Trackhouse Racing team have never been in this position before.
He hasn't won a Cup race since April, but that fact can be misleading. The driver of the No. 1 Chevrolet has been in contention all year and leads the field in top-fives at 13 and top-tens at 19 (where he is tied with Chase Elliott).
After narrowly escaping elimination after an unforced error in the Charlotte Roval, Chastain has been on it in the last two weeks. A second-place finish at both Las Vegas and Homestead puts him 19 points above the cut line, ahead of all other drivers who have yet to lock themselves in.
At Homestead, it was an uphill climb from 20th on the grid following a poor qualifying effort, where he placed lowest of all playoff drivers.
"Not the way you would have scripted it," said Chastain post-race. "I feel like we had a top 3 or 4 car all day, all weekend, and a little too tight in qualifying, and come behind that with a driver that chose the completely wrong lane in (Turns) 3 and 4, against everything I've ever trained for and prepared for. Qualified 20th, and it took us all day long.
"We need to get the car turning better from qualifying into the race. We were too tight. (Crew chief) Phil Surgen and this whole Kubota team got it turning better, and pit stops were incredible again. Our guys were just -- they're just rock stars on pit road, and I'm so glad to go to battle with them."
The only part of his performance that can be criticized is a lack of stage points, with Chastain collecting just three during Sunday's race.
"At the end of the day, I know we didn't score a ton of stage points," he said. "We put ourselves in position at the end, and just keep executing. I almost spun off Turn 2 in front of Daniel (Suarez), and I had my arms all crossed up and I just took a deep breath down the back, and thought, what can I control here? I can control not spinning out, so let's go a little slower next time, and had a shot at it."
NASCAR now heads to Martinsville for a 500-mile short track race to decide which four drivers will get to fight for the championship at Phoenix. Joey Logano has already secured his place, but it's Chastain leading regular season champion Elliott (+11pts) and then William Byron (+5pts) as the remaining three drivers above the cut line.
Denny Hamlin is just five points out, Ryan Blaney 18 points below, Christopher Bell 33 points behind and Chase Briscoe 44 points adrift of the cut line.
Chastain finished fifth at Martinsville earlier this year, but he's still unsure of how to feel entering the pivotal cut-off race.
"I don't know," he admitted. "What's it supposed to feel like? I've never been here ... for Trackhouse, we're learning all this together; we're experiencing this together. We've got a lot of knowledge in our shop and I'll lean on a lot of teammates, both in the GM camp and inside our shop of how to approach it, but I'm a racer. We're just going to race. Go practice as well as we can; we'll go qualify as best we can. And I'm late all the time, so a grandfather clock might do me a little good for the rest of my life."
To advance into the final four would be a "life goal" realized for Chastain, who spent years in lower-tier equipment fighting for an opportunity to compete for race wins -- and championships.
He continued: "Just to make it to the Cup Series, be here competing with my heroes. I train with Kyle (Larson), and he was better than us today. But he ran into the 19 (Martin Truex Jr.), knocked his diffuser flap down and he didn't have quite as much grip, and we had a shot at it.
"I feel like that no matter what, this season is going to be a success, but in the moments where I hit the wall at the Roval and I realized this could all be gone and we could not transfer, it hurts, and I don't want that. I'm a racer, and I want the next thing.
"I feel confident in our group and what we'll take to Martinsville. We ran fifth there in the spring. We just continue to arrive on the scene of the Cup Series, and I wouldn't want to be doing it with anybody else."
