LAS VEGAS – If you’d asked Cole Custer as a kid whether he thought he’d eventually break into the Monster Energy NASCAR Cup Series, he’d probably have told you that it was a dream of his, but it wasn’t very likely to actually happen.

Now, at 20 years old, Custer will see those dreams finally realized when he straps in for Rick Ware Racing to compete in Sunday’s Pennzoil 400 at Las Vegas Motor Speedway.

Custer, who competes full-time for Stewart-Haas Racing in the NASCAR Xfinity Series and scored his first win during last year’s season-finale at Homestead-Miami Speedway, will drive the No. 51 Haas Automation Ford as he makes his debut at the premier level of stock car racing in the United States.

As he prepared to fly out to Las Vegas this week, Custer took time to soak in the magnitude of the journey he’s about to embark on, still in disbelief over the fact that he’s got a shot among the best of the best that NASCAR has to offer.

“It’s pretty unreal to think about,” said Custer of making his Cup Series debut. “I was a kid that never even thought I’d make it to this level, but now, here we are. I’m really looking forward to it. I think it’s going to be a learning experience, for sure, but I’m ready for it and hopefully we can make the best of our day, run all the laps and see what we come out with at the end of it.”

The effort will be a collaboration between Rick Ware Racing and Stewart-Haas, which already fields four full-time cars in the Monster Energy NASCAR Cup Series for Kevin Harvick, Aric Almirola, Clint Bowyer and Kurt Busch.

It’s something that Custer said has been in the works since around the Christmas holiday, and was further hinted at when Custer stepped in to drive the Go FAS Racing No. 32 Ford during an organizational test session at Las Vegas in January, carrying RWR logos on his firesuit.

“We started talking about this mid-way through the offseason; everyone at Stewart-Haas Racing wanted to get me a little bit of Cup experience so I could get my feet wet in it a little bit,” explained Custer. “The offseason is the time for that, when you start thinking about things that you can do for next season and this is one of the things that came out of those discussions.”

Custer’s fastest lap during the open test was a time of 28.914 seconds (186.761 mph), placing him 10th overall among 16 drivers and within half a second of most of the frontrunners.

While it wasn’t flashy, Custer said the two-day test gave him plenty of opportunity to get comfortable in a Cup car ahead of his debut.

“Being able to go to the Vegas test, get a feel for what the Cup car is like and shake it down was pretty huge for me, I think. Now, going back, I feel like we should be fairly solid. By the end of the second day of testing, I felt like we were right in the mix with everybody. As long as we do everything right and try not to make any mistakes, I think there’s no reason we can’t have a solid day.”