Dani Pedrosa took his fourth victory of the season, and first ever back-to-back race wins, with a lights-to-flag triumph at Misano on Sunday.
But there were no celebrations as the news that Shoya Tomizawa had lost his life in the earlier Moto2 event was announced immediately after the finish of the MotoGP race.
Podiums flags were flown at half mast and there was no spraying of champagne as a mark of respect to the young Japanese, who won the first ever 600cc grand prix at Qatar this year.
Pedrosa had converted pole into the race lead at turn one and was one-second clear by lap three of 28.
World championship leader Jorge Lorenzo dropped from second to third at the start, but re-passed Ducati's Casey Stoner later in the opening lap and remaining in second for the rest of the race.
Pedrosa's lead over Lorenzo topped five seconds through the middle stages before he backed off to a 1.900sec victory at the chequered flag.
Lorenzo's title lead over Pedrosa has now been reduced from 68 to 63 points with six rounds to go.
After the race, Pedrosa spoke of his deep sadness at the loss of Tomizawa, whose death comes just one week after Peter Lenz was killed in a support race at Indianapolis.
The fight for third was closer than the lead, with local legend Valentino Rossi - who overtook Stoner on lap eleven - facing an assault from countryman Andrea Dovizioso with ten laps to go.
Pedrosa's team-mate remained glued to the #46 until the penultimate lap, when Rossi built a one-second lead over the Honda rider - enough to prevent a last lap lunge.
Stoner's pace dropped off markedly in the second half of the race and the Ducati rider took the flag twelve seconds behind Dovizioso, but almost ten ahead of top satellite rider Ben Spies.