A sprint race win and a second place in the feature race for Aiello gave him the advantage over Leslie's second and fourth places, so the fight for the drivers' title goes down to the wire at the final rounds at Silverstone next Sunday.
The day's other winner - Honda's James Thompson -- had a mixed day winning the feature race in dominant style after being excluded from third place in the sprint following a 105mph run-in with Jason Plato.
Aiello made the most of his own excellent start and Leslie's poor getaway to win the sprint race. Leslie, Thompson and Plato ran side-by-side for much of the time, with each ahead at one point or another. The battle was resolved in Leslie's favour as Thompson and Plato clashed and the Renault bounced across the grass and into retirement. Thompson was later thrown out of the results and fined pounds 1,000 for his part in Plato's demise.
Livid at his sprint race fate, Thompson drove the feature race at a furious pace and Aiello soon settled for second.
Aiello's lead is now effectively 28 points and with just a maximum of 33 left to win, the title is almost his. "Almost is not enough," he said. "I will keep my concentration and drive for the championship at Silverstone."