Williams Esports took both victories as The Race IndyPRO Championship by Formula SimRacing kicked off on the Indianapolis road course.
Petar Brljak won the opening sprint race by opting for a different tyre strategy to most.
He qualified in sixth but as the only driver in the top 13 to start on the softer tyres, he picked off those ahead of him one by one until he got to the front.
When he overtook Alex Siebel for second place he was four seconds behind leader Alen Terzic of the Jean Alesi Esports Academy team.
Brljak closed down that gap at the rate of one second a lap, passing Terzic with a late braking move into Turn 1 to take the lead of the race by hugging the apex around the first corner.
Terzic, the 2015 Formula SimRacing world champion, and Siebel completed the podium.
GPVWC Superleague race winner Adam Maguire started the race in 14th, but the decision to opt for the soft tyres in the sprint race meant he finished the race five places higher up.
Crossing the line in ninth place proved to be crucial as the race results from the sprint race determined the starting grid for the feature race, but with the top nine finishers reversed.
By starting on the softer tyres Maguire pulled away from pursuers Jiri Toman and Dennis Jordan who opted for the harder compound.
Williams Esports’ Martin Stefanko also started on the softer tyres and took six laps to get into second place, and a further five laps to catch up and slipstream past Maguire for the race lead.
By starting on the softs, Stefanko had to complete the rest of the race on the harder tyres whereas many of the other frontrunners were able to end the race on the softs.
After the first round of pitstops Toman was in first having pitted earlier than all of the other frontrunners.
But for the second and final pit phase it proved to be beneficial to stop later and take on less fuel, minimising time in the pitlane.
Jordan stopped for the final time four laps after Toman to move into second on circuit and become the leader of the soft tyre runners.
Stefanko’s last pitstop took place a further six laps after Jordan’s, late enough to put Stefanko back out in first but on the hard tyres.
With a one second gap and six laps of the race still to run, Stefanko’s chances of retaining the lead of the race were looking slim.
However Jordan locked up under braking for Turn 1, half-spinning the car and extending Stefanko’s lead to over three seconds.
After his mistake Jordan wasn’t able to catch back up to Stefanko in the final few laps, handing the Williams Esports driver the first feature race win of the championship.
Jordan crossed the line in second with Toman in third after Jernej Simoncic was unsuccessful in his attempts to move into the podium places on the final lap.
Brljak was on course to finish in fifth, but contact with Siebel into Turn 7 in the closing stages of the race meant Brljak was forced out onto the grass where he dropped to sixth in the other Williams Esports car.
The second race of the IndyPRO championship will be held at Portland International Raceway on September 27.
