Britain's Cal Crutchlow (LCR Honda) on Saturday won pole position for the Spanish Grand Prix, after clocking the fastest time in the second MotoGP qualifying session.
With 11 laps to go Marquez has a 1.3-second advantage over Lorenzo, and then a Ducati disaster with 8 laps to go as a huge crash unfolds and Dovizioso, Pedrosa and Lorenzo are out of the race.
Pedrosa, who underwent wrist surgery less than a month ago, was thrown high over his bike and onto the asphalt after trying to go past the two Ducatis on the inside of the sunny Jerez circuit in southern Spain.
When all three were collected by the crash later on, Tech 3 Yamaha's Johann Zarco was promoted into a comfortable second, despite having seemingly struggled in the early going.
"I saw Lorenzo braking so late and exiting so well from the corners but when I saw his tyres start to drop, I decided to make a move to lead the race and open a gap", he added.
With a full house the race starts with Lorenzo taking the lead and poleman Crutchlow slipping back to fourth.
The Suzuki podium was the team's third in a row, showing they're for real this year. Dovizioso dropped to fifth overall with 46.
"I was convinced before the race that I was able to win", explained Marquez.
He said, "Here the race is very long and you have to manage many things", adding that the Spanish GP was "not a race about speed" but a race where being "precise" and making "the correct decision in every lap" was the key to victory.
Seven-time world champion Valentino Rossi was fifth in a race during which he reached a career milestone by completing the circumference of the planet in race kilometres.
"Were the other guys on the outside coming back from a mistake, re-joining the right line? Yes". The one on the inside.