Criville, who started from the third row of the grid after managing only the 10th fastest time in qualifying, fought his way through the pack on his Honda and was soon close behind Roberts, but he was never given the chance to squeeze by and had to be content with second place, just 0.338sec behind. Japan's Norick Abe was a distant third.
Roberts, who won the first two races of the year, had gone six without a victory before yesterday.
Criville, who had won five of the previous six races, stretched his championship lead to 47 points as his team- mate and main rival Tadayuki Okada, of Japan, crashed out on the 15th lap. Criville tops the standings with 174 points, while Roberts moves into second on 127,with Okada third on 113.
There was another thrilling battle in the 250cc race, in which the Italian Aprilia rider Valentino Rossi edged out his compatriot and Honda rival Loris Capirossi to seize the championship lead. Rossi, who was scoring his fourth win of the season, has 165 points, 18 more than the Japanese Tohru Ukawa, who crashed out on the second lap on his Honda.
On a fine day for Italy, the impressive teenager Marco Melandri, who is only 16, won his first race of the year in the 125cc class.
The next meeting is the Czech Grand Prix on 22 August, for which Michael Doohan hopes to return.
At Oulton Park, Sean Emmett re-wrote the British Superbike Championship record books as he claimed the narrowest-ever winning margin in the second race of the seventh round. Emmett held off the challenge of the series leader, Troy Bayliss, by just 0.001sec.
It was Emmett's first victory of the season and a race the Ducati rider described as "my best ever, just fantastic". Bayliss, who looked to have the edge as they went into the final lap, said: "It was the hardest race ever. It was one that we both wanted to win. Great."
John Reynolds, who had won the opening race, just ahead of his team-mate Emmett, took third place to move into second in the rankings.
The defending triple champion Niall Mackenzie's disappointing season continued. The Scot, who had qualified his Yamaha fourth fastest, had moved into third place in the opener but slid out on the fifth lap, sustaining shoulder injuries which ruled him out of the second race.Reuse content