MotoGP championship leader Marc Marquez profited from a big collision that wiped out four rivals to win the Catalunya Grand Prix on Sunday.
A hotly contested start gave way to a Marquez procession after Repsol Honda team-mate Jorge Lorenzo caused chaos at turn 10 on just the second lap in Barcelona.
Pole-sitter Fabio Quartararo - who underwent arm pump surgery just 12 days ago - also benefited to claim his best career finish in second, having again threatened to fail to build on a strong display in qualifying, as Andrea Dovizioso, Maverick Vinales and Valentino Rossi were taken out by Lorenzo.
Reigning champion Marquez boosted his advantage in the riders' standings to 37 points on a hugely damaging day for his closest rival Dovizioso, while only 13 bikes finished.
Dovizioso had led the way from the first corner, moving clear of Marquez and Vinales as Quartararo slipped to a disappointing eighth.
But Lorenzo's charge changed the course of the race. He looked to go down the inside and clipped Dovizioso, with the pair consequently nudging Vinales and Rossi out of action.
That incident left Marquez in the clear and the five-time champion never looked like letting his advantage slip.
The remaining excitement instead came in the tussle to join the Honda star on the podium, with Alex Rins overtaking Quartararo and then attacking Danilo Petrucci.
Rins finally got through with 11 laps to go, but Petrucci hit back and contact between the two saw the Spaniard struggle to stay upright and fall down the field.
Quartararo, who had been holding off Jack Miller for fourth, again capitalised and moved into second for an ultimately positive finish to an eventful ride.
Clear at the front, Marquez, having earlier seen brother Alex secure a third straight Moto2 victory, was untroubled and eased home.
1. Marc Marquez (Repsol Honda)
2. Fabio Quartararo (Petronas Yamaha) +2.660secs
3. Danilo Petrucci (Ducati) +4.537s
4. Alex Rins (Suzuki Ecstar) +6.602s
5. Jack Miller (Pramac Racing) +6.870s
6. Joan Mir (Suzuki Ecstar) +7.040s
7. Pol Espargaro (Red Bull KTM Factory Racing) +16.144s
8. Takaaki Nakagami (LCR Honda) +17.969s
9. Tito Rabat (Reale Avintia Racing) +22.661s
10. Johann Zarco (Red Bull KTM Factory Racing) +26.228s
1. Marc Marquez (Repsol Honda) 140
2. Andrea Dovizioso (Ducati) 103 (-37)
3. Alex Rins (Suzuki Ecstar) 101 (-39)
4. Danilo Petrucci (Ducati) 98 (-42)
5. Valentino Rossi (Monster Energy Yamaha) 72 (-68)
1. Ducati 201
2. Repsol Honda 159 (-42)
3. Suzuki Ecstar 123 (-78)
4. Monster Energy Yamaha 112 (-89)
5. LCR Honda 90 (-111)