The Spaniard was comfortably the fastest man in the race, but was made to work hard for the win by Tech 1 Racing’s Charles Pic.
Competing in only his third World Series round of the season, Guillaume Moreau completed the podium for newcomers SG Formula, harassing a flu-ridden Pic to the finish.
Alguersuari positioned his car at an angle on pole position to counter a possible attack from Pic away from the line. His efforts were in vain however, as Pic powered into the lead on the downhill run into Turn 1.
Alguersuari retook first position when the Frenchman ran wide at the back of the circuit, and made full use of a new set of tyres to build a cushion of 5.9 seconds.
A safety car period on lap 16, while the damaged cars of race one winner Jon Lancaster and Anton Nebylitskiy were removed, undid all of Alguersuari’s work. Pic seized his chance on the restart three laps later to briefly retake the lead, but the Red Bull driver put in an immediate, and successful, counter on the exit of Turn 1.
“I think it was a nice race for both of us in the end," said Alguersuari. “It was quite a clean race, and I could just get by into Turn 2. Obviously, Formula 1 is going quite well for me. World Series gives me good feedback and I am learning all the time as my experience increases.
“There are always many competitive drivers here, some in their second and third year. The team have worked hard to improve the car in qualifying and I hope we can stay up here for the final two meetings."
Ultimate Motorsport’s Miguel Molina repeated his inspired performance from race one to finish fourth from tenth position on the grid, ahead of championship leader Bertrand Baguette.
Alguersuari’s Carlin team-mate Oliver Turvey drove through the pain barrier caused by a bruised hand, the result of a collision in race one, to finish sixth.
Alguersuari’s win lifts him one point ahead of compatriot Marcos Martinez into third position in the championship. Martinez retired in the pits on lap four.