In sweltering hot conditions, with the track temperature over 40'C and grip a concern for all the riders, Lorenzo made a flying start from third, dogged by the Honda of Marquez.
The duo began to etch out a small advantage over the pack only for it to become a one-man lead when Marquez – running too hot – almost hit the back of the 99 and had to take evasive action. That resulted in him running off the track and crashing at Turn 10.
Marquez' demise meant Lorenzo held a 1.4s advantage over second place, which was Valentino Rossi as the Italian easily sliced by Andrea Dovizioso to make it a Yamaha 1-2. As the field struggled for grip on the hot asphalt the Ducati rider's challenge ended soon after when he lost the rear through Turn 4.
With their rivals lacking the grunt needed to get involved in the battle at the front, Lorenzo and Rossi raced to the 1-2 for Yamaha with the Spaniard taking it by a mere 0.885s over the Italian.
The result has added some spice to the championship battle as, after seven races, the team-mates are separated by just one point in Rossi's favour. Momentum, though, is firmly with Lorenzo after his fourth win on the trot.
"It is very hot, all weekend we didn't have the temperatures we had today," said Lorenzo. "I pushed so hard, Valentino made me push so hard."
Dani Pedrosa salvaged some pride for Honda as he completed the podium ahead of Andrea Iannone and Monster Yamaha Tech 3's Bradley Smith.
Maverick Vinales, who started second on the grid but lacked the power needed to deliver on his qualifying pace and dropped to P14 on the opening lap, brought his Suzuki home in sixth.
Scott Redding recorded his best result for Marc VDS as he was seventh ahead of Stefan Bradl, Danilo Petrucci and Alvaro Bautista.
There were several retirements with Cal Crutchlow joining Marquez and Dovizioso in the dirt as did Pol Espargaro. Yonny Hernandez, Marco Melandri and Nicky Hayden also failed to reach the chequered flag.
There was also disappointment for pole-sitter Aleix Espargaro. The Suzuki rider crashed out with five to go while running in fourth place.
1 Jorge LORENZO Movistar Yamaha MotoGP 42'53.208
2 Valentino ROSSI Movistar Yamaha MotoGP 0.885
3 Dani PEDROSA Repsol Honda Team 19.455
4 Andrea IANNONE Ducati Team 24.925
5 Bradley SMITH Monster Yamaha Tech 3 27.782
6 Maverick VIÑALES Team SUZUKI ECSTAR 29.559
7 Scott REDDING EG 0,0 Marc VDS Honda 36.424
8 Stefan BRADL Athinà Forward Racing 42.103
9 Danilo PETRUCCI Octo Pramac Racing 49.350
10 Alvaro BAUTISTA Aprilia Racing Team Gresini 52.569
11 Jack MILLER CWM LCR Honda 53.666
12 Eugene LAVERTY Aspar MotoGP Team 55.765
13 Loris BAZ Athinà Forward Racing 55.832
14 Mike DI MEGLIO Avintia Racing 1'09.037
15 Alex DE ANGELIS E-Motion IodaRacing Team 1'25.263
16 Hector BARBERA Avintia Racing 1 Lap
Aleix ESPARGARO Team SUZUKI ECSTAR 5 Laps
Nicky HAYDEN Aspar MotoGP Team 12 Laps
Marco MELANDRI Aprilia Racing Team Gresini 19 Laps
Andrea DOVIZIOSO Ducati Team 19 Laps
Pol ESPARGARO Monster Yamaha Tech 3 21 Laps
Marc MARQUEZ Repsol Honda Team 22 Laps
Cal CRUTCHLOW CWM LCR Honda 22 Laps
Yonny HERNANDEZ Octo Pramac Racing 23 Laps