Marquez continued untroubled up front to clinch victory easily and make it six wins out of six at the Grand Prix of Americas.
His lead peaked at around sevens seconds, and he controlled the gap from thereon to take his first win of the 2018 season and his 12th straight triumph on American soil by 3.5 seconds.
"I went out, and unfortunately I didn't expect Maverick to arrive behind me because I was focused on Andrea (Iannone), who was waiting ahead and who I knew could be very fast", Marquez said.
Maverick Vinales, who started on pole for Yamaha, finished second and 3.560 seconds behind his compatriot while Italian Andrea Iannone was third in his first podium with Suzuki. "So tomorrow I'll start from fourth".
The Suzuki man's time in the lead proved short-lived however, as Marquez got by at Turn 12 on the opening lap. Soon after Marquez overtook Iannone and checked out in style - he was not going to be seen again by the rest of the grid until the end! Behind him, there wasn't much action either.More news: Mitt Romney Fails to Get Senate Nomination at Utah GOP Convention
Dovizioso managed to find a way past Johann Zarco to come home in fifth place behind Rossi.
Marquez's Spanish team mate Dani Pedrosa, who had surgery on a broken wrist last week after crashing in Argentina, will start ninth on the grid.
The former champion was also passed by Tito Rabat and Aleix Espargaro, and ended his day in 11th, while Rabat went on to steal eighth from Miller. Maverick Vinales is not too far behind with 41 points, while last race victor Cal Crutchlow is fourth at 38 point - he made no improvements today and finished outside of points.
British rider Cal Crutchlow, who leads the championship after two races, qualified seventh for the non-works LCR Honda team.
The next race is in Jerez in two weeks' time and that's where the real battle will commence!