CONCORD, N.C. — Kyle Larson arrived to Charlotte Motor Speedway just in time for lightning and rain to end his chances of competing in the Indianapolis 500 and NASCAR’s Coca-Cola 600 in the same day.

That left longtime Xfinity Series driver Justin Allgaier in the driver’s seat of the No. 5 Hendrick Motorsports Chevrolet for all 249 laps of Sunday’s rain-shortened Cup Series race on the way to a 13th-place finish in his first Cup start in two years.

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As Larson’s plans came together through both Hendrick and IndyCar’s Arrow McLaren programs, Allgaier was along for the ride in a reserve role, including the reception of a HendrickCars.com fire suit over the winter.

Still, when circumstances became obvious Sunday afternoon that Allgaier would need to at least start the No. 5 Chevrolet after a four-hour rain delay in Indianapolis, Allgaier had to shake off the pressure of keeping the car in one piece if and whenever Larson arrived at the track.

“If he would have come at Lap 25 or 50, when I was still not comfortable, that would have been a hard thing for me to swallow,” Allgaier said. “So as much as it stinks that he wasn’t able to run more laps in the race, I just thought it was good for me because I finally got to where I was comfortable. And I can step out of this race car and be perfectly content with how the day went.”

Larson was unavailable for comment post-race Sunday, but issued a lengthy statement Monday morning on his social media platforms that read in part: “What I thought could be one of the best days of my life quickly turned into one of the most disappointing ones I’ve ever experienced. … So much time, money and effort went into this experience and it just kills me to have it all end the way it did. I feel like I let so many people down. We knew all along weather could throw a wrench into things but seeing it come to reality is a horrible feeling.

“Up until Sunday it was truly one of the greatest experiences of my life. I can’t describe how appreciative I am of everyone’s support of me to live out a dream. I hope it’s not the last opportunity I have to try the Double but if it is I guess it was memorable.”

While Larson was battling weather all day in Indianapolis, crew chief Cliff Daniels was running the show in Charlotte.

Daniels has had to adapt to working with three separate drivers across the past two weeks, including Kevin Harvick for practice and qualifying at North Wilkesboro Speedway’s NASCAR All-Star Race, Allgaier at Charlotte and Larson at both. But his steady leadership prevailed, particularly in the early stages of Sunday’s race as he verbally coached Allgaier around the track using SMT data. That included properly placing the car in certain lanes, recommending brake pressures and passing maneuvers.

“He is very buttoned-up and he says all the right things and he does all the right things,” Allgaier said. “He’s very positive on the radio. But I told Cliff before the race, I said, ‘Listen, I don’t know what I’m getting into. The last thing I want to do is wreck this thing, right? I have not fooled myself enough to know that I don’t need help. So, any little piece of advice that you can give me along the way, make sure you tell me because the only way I’m going to get better is to have direction from you and what everybody else is doing.’ ”

Daniels obliged, and the improvement from Allgaier’s early laps to the premature checkered flag was glaring as Allgaier worked from fighting from the tail end of the lead lap all the way to a 13th-place charge.

“Justin had a lot of guts to come in and do the job that he did and be as focused and do all the things to get up to speed as well as he did,” Daniels told NASCAR.com. “It’s no secret he’s the Chevrolet test driver. And it’s one thing to get to know these cars, which he has in a test environment. But in a race environment, they are so different. The pack is different. For him to come in and get up to speed the way he did was really impressive, and we’re very appreciative of the job that he did. And let’s be honest, once he got comfortable, he was coming to the front. He was doing a really good job, so very proud of him.”

Fresh from Indiana, Hendrick Motorsports’ president and general manager Jeff Andrews offered his praise of the 37-year-old Illinois native, underscoring the difficulty of jumping into a car with limited experience.

“Justin did an amazing job for us,” Andrews told NASCAR.com. “I mean to step in in those conditions, not having practiced or qualified the car and step in and do what he did, we couldn’t be more pleased with him. He does a lot of work for us, obviously, on the testing side and driving the Chevrolet wheel force transducer cars, so we’re very familiar with him, and I’ve used him for many years in these situations. But this one was probably the — I just can’t iterate enough what a great job he did for us bringing that car home in 13th place.”

The logistics of Larson’s plans were complicated by weather throughout each of Sunday’s two events. While Hendrick Motorsports had put over a year’s worth of plans together, Mother Nature ultimately had the final say.

“Obviously, the weather messed with us, not only there but again here, and it’s unfortunate,” Andrews said. “It’s not the way we wanted this whole situation to go. Kind of (felt) like we were well-prepared to handle all the travel logistics and do what we needed to do to run both races and it just wasn’t meant to be. We can’t change the weather or work on that. But all in all, proud to go up there. Proud of the effort to those guys put in.”

Larson finished 18th in his inaugural Indianapolis 500 attempt, a run slowed by a speeding penalty in the latter stages of the 200-lap affair. But ultimately, the longtime sprint car racer opted to start the 500-miler despite its delayed start.

“We kind of knew what we were going to be faced with there as far as being committed to running Kyle in the 500 and it starting late,” Andrews said. “We just hoped to be able to get back here to let him have a couple hundred laps in the car here to see what he could do. So, unfortunate.

“I feel bad for him. He’s pretty dejected right now, but he needs to hold his head high. He did a great job today, and weather is what it is. So we’ll just take what he gave us and learn from it and talk about if we want to do it next year or not.”

As the No. 5 team’s leader, Daniels was tasked with making sure the car and its driver — whether it be Larson or Allgaier — excelled. Asked whether he would describe Sunday as stressful or otherwise, Daniels took perhaps his first moment all day to ponder how he actually felt about the day, all at the ripe time of 11:59 p.m. ET.

“I don’t know,” he said, the only interruption in a 12-second pause. “I don’t get paid to put a lot of emotion — I feel like stressful is an emotional term. Like, we had a job to do, and that was our focus. There were a lot of boxes we had to check, a lot of details that had to be met, coordination with our team and logistics and NASCAR, and there’s a lot of moving parts. So, never at any point did I even have a minute to sit down and think, like, what do I feel right now? I don’t get paid to have feelings here at the race track. You know what I mean? You have to hit the marks you have to hit.”

While circumstances kept Larson from climbing into his Cup car, Allgaier hit all the marks he needed by the end of his rain-shortened return to the Cup Series.