Minutes after they finished the Verizon IndyCar Series season opener at St. Petersburg, Fla., Sebastien Bourdais, Scott Dixon and Ryan Hunter-Reay traveled to Birmingham, Ala., for a test session at Barber Motorsports Park.

By Wednesday, they were back in Florida practicing for Saturday’s Mobil 1 12 Hours of Sebring.

Welcome to the busy world of crossing over, the practice of driving in other forms of motorsports while attempting to maintain focus on the primary job. IndyCar drivers won’t return to the track until April 1 at Phoenix International Raceway, so the downtime this weekend allows some to participate in the historic sports car endurance race at Sebring International Raceway.

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Imagine an NBA player using his days off to participate in another basketball series, with slightly different rules, a different ball and court, and different yet just as talented opponents.

“It does keep you sharp,” Dixon told USA TODAY Sports. “You have to be quite cognizant of keeping things in check, whether it’s procedures or the way the different teams run. As long as you’re not getting too overrun or not traveling too much, I think it is beneficial. If you can learn different things from crossing over, it can inspire different things in your everyday job.”

When the 64th annual race gets underway Saturday at 10:40 a.m. ET, Dixon, Bourdais and Hunter-Reay will join Spencer Pigot as IndyCar drivers crossing over, while several others — including Dixon’s teammate, Ryan Briscoe — have extensive IndyCar experience on their resumes.

Perhaps nobody has more experience with crossing over than Bourdais. The four-time CART/Champ Car champion and former Formula One driver has 16 years of experience in various sports car categories and races, including three runner-up finishes in the 24 Hours of Le Mans. He’ll return to his hometown race in June for the 11th time in his career. Dixon, the reigning IndyCar champion, will attempt it for the first time.

“I’ve been doing it for a long, long time now, so it doesn’t really bother me at all,” Bourdais told USA TODAY Sports. “It’s actually made me a better driver overall. Every track and condition makes you experience something different. It sharpens you when you learn to adapt to different tracks and conditions — different everything — rather than being stuck in a groove where you’re in your little comfort zone. You grow as a driver.”

Hunter-Reay, who finished third Sunday in the Grand Prix of St. Petersburg, returns to the No. 90 VisitFlorida Racing Corvette DP, which finished third overall in the IMSA WeatherTech SportsCar Championship season opening Rolex 24.

For Bourdais and Dixon, the change is more dramatic. Instead of their usual Prototype entry, the two will be behind the wheel of two Ford Chip Ganassi Racing cars in the GT class.

“It’s somewhat easier for me because it’s the same team,” Dixon said. “It’s a lot of the same people I’ve worked with before. You just have to be sure that you keep that separation in your mind. The cars — especially if you’re looking at a GT — are very, very different. With the Prototype and the Indy car, there were a lot more similarities.”

Ganassi, who owns teams in IndyCar, NASCAR and IMSA, routinely lets his NASCAR and IndyCar drivers change to seats in sports cars, especially at Daytona and Sebring. In January, Dixon, Larson, McMurray and IndyCar regular Tony Kanaan teamed up in the Rolex 24, which they won in 2015.

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“Do I want to necessarily have IndyCar drivers in sports cars or stock car drivers in sports cars? No, I couldn’t care less,” Ganassi told USA TODAY Sports. “But if you have successful ones, I think it brings some cache. If you can bring a Dixon, a (Dario) Franchitti, a (Kyle) Larson, a (Jamie) McMurray — guys that have some wins — that adds a little cache. It’s always been done, historically.”

There’s another advantage to crossing over — seat time. The 2016 IndyCar season will last just six months, and testing is strictly limited; sports car racing — especially endurance events — give drivers valuable time in a race car.

“The IndyCar season is so short,” Bourdais said. “Doing sports cars gives us a lot of miles and time behind the wheel. It gets you back into things mentally and physically. It’s a big help.”