When the lights went out it was Rossi who got a stellar launch from P2, with pole man Zarco slightly sluggish off the line and ‘The Doctor' getting a comfortable holeshot ahead of the the Frenchman, who managed to brake late to slot into P2.
Jack Miller (Alma Pramac Racing) was able to leapfrog Andrea Iannone (Team Suzuki Ecstar) into P3 at the start, with Marquez making up one position into P6.
The premier class riders then settled, but this came after Marquez and team-mate Dani Pedrosa (Repsol Honda Team) exchanged paint on the opening lap.
The 2018 champion would soon start to make his way forward though, despite a hairy last corner moment at the end of the opening lap that led to Iannone crashing out directly behind the seven-time champion.
Back at the front, Rossi and Zarco were off as Yamaha had a 1-2 in the opening exchanges, but Marquez hunted them down after making his way past Miller.
The Honda rider was on the exhaust of Zarco's M1 machine and soon enough he managed to slice his way through.
With five laps to go, the gap between Rossi and Marquez was just 0.7, as the stage was set for a grandstand finish between two of the sport's all-time greats.
But then, disaster struck ‘The Doctor'. A return to victory after 26 races went begging as he lost the front of his YZR-M1 at Turn 1 with four laps to go and he picked up his stricken Yamaha in front of the Rossi grandstand, leaving Marquez with a lonely ride home to the win.