Alfonso Celis Jr. embarks on what he hopes will be a career-defining moment when he makes his Verizon IndyCar Series debut this weekend in the KOHLER Grand Prix at Road America.

The 21-year-old Mexican, a former development driver in Formula One, started becoming acquainted with Indy cars at a test last week for Juncos Racing at the scenic 4.014-mile, 14-turn permanent road course in Elkhart Lake, Wisconsin. It comes after Celis drove for team owner Ricardo Juncos in the Indy Lights presented by Cooper Tires doubleheader weekend at Barber Motorsports Park in April.

Juncos was impressed by his Celis’ quick acclimation to the Indy car’s universal aero kit, among other things.

“For me, it’s good now after he did the test,” Juncos said. “He performed well, (gave) very good feedback. You know, it’s not easy to jump in an Indy car and do that at a Road America track which is also a new track for him. He had never been there before.

“It was quite good, quite surprising, so we’re pretty confident for this weekend to be honest.”

KOHLER GRAND PRIX: Entry list

Juncos has known Celis since he tested a Pro Mazda car for the team in 2014 and went to the top of the charts instantly. Celis’ path veered to Europe, however, where he spent two years with Sahara Force India as its Formula One test driver, learning the ins and outs of the technical aspect of racing.

It’s those qualities that made an impression on Juncos, who admitted that the two “debriefed for hours” following the Road America test.

“In general, I was expecting it to be fun, but not that fun,” Celis said of driving the No. 32 Juncos Racing Chevrolet. “The car is just awesome to drive. I was really, really pleased. Feeling wise, it’s one of those cars that you will always remember.

“There’s a lot to take in. Obviously, I’m coming halfway in (to the season) pretty much with no testing – just one day in the car, getting to know the procedures – but there’s a lot to take in and I have to be quite patient to not get frustrated and let the learning process come.”

Celis admits to admiration for fellow Mexicans who drove during Indy cars in the past, including Mario Dominguez and fan favorite Adrian Fernandez. He said he turned to David Martinez, who scored three top-10 finishes in four Champ Car World Series starts for team owner Gerald Forsythe, for advice and mentorship during the test.

Fellow Verizon IndyCar Series rookies Rene Binder and Kyle Kaiser have each driven the Juncos entry in four races this season. The best result for each was 16th place (Kaiser at Long Beach and Binder at Barber), as the team aims to become a full-time entry in 2019.

Celis scored a win, seven podiums and a pole on his way to third place last year in the Formula V8 3.5 Series championship. Juncos isn’t sure what the driver’s future holds with the team following Road America.

“At the moment, there is nothing on the table other than this weekend, so I think we just focus on this coming weekend,” Juncos said.

“For him, it’s going to be huge. First time ever (to race an Indy car) and that’s like everybody else, so he has the pressure to be the first time, not make mistakes and try to finish. That’s the way we were with Kyle and Rene. We’re just going to focus on finishing the race, make the most of the laps and learn as much as possible from the weekend.

“After this weekend, we’re going to sit down and talk to his father, (his) sponsors and himself. We’ll see what else we can do, if anything, but at the moment it’s only Road America and we’re going to try and focus to be good there.”

The Verizon IndyCar Series schedule for Road America calls for two practices on Friday (starting at noon and 4:15 p.m. ET), with a third practice on Saturday (noon) ahead of Verizon P1 Award knockout qualifying (4 p.m.). All practices and qualifying stream live on RaceControl.IndyCar.com, youtube.com/indycar and the INDYCAR Mobile app. A same-day qualifying telecast airs at 6:30 p.m. on NBCSN.

Live coverage of Sunday’s 55-lap race begins at 12:30 p.m. on NBCSN and the Advance Auto Parts INDYCAR Radio Network.