Ducati rider Jorge Lorenzo scored his second consecutive MotoGP win in Barcelona, converting pole position into a dominant triumph after a short battle with Marc Marquez.
Lorenzo led every lap but the first in a particularly attrition-heavy race, with not enough classified finishers to fill out the points-scoring top 15.
The three-time world champion is now level on points with teammate Andrea Dovizioso, who crashed, and is 49 points behind Marquez – who leads nearest rival Valentino Rossi by 27 points.
Famed for his quick starts, Lorenzo was expected to head the field into Turn 1 from pole, but instead gave up the lead to Marquez off the line, before dropping behind Andrea Iannone as well.
Iannone then challenged Marquez for the lead at the sharp Turn 10 left-hander, braking late down the inside but running well wide, allowing Marquez to keep the lead and Lorenzo to take second.
Lorenzo then lined up Marquez for a move on the start-finish straight, using the slipstream and Ducati's straightline prowess to reclaim the lead.
But an expected Lorenzo breakaway did not follow in the next few laps, with Marquez running right on his future Repsol Honda teammate's tail.
The pair had soon broken away from all but Dovizioso, who managed to just about stay in touch with Marquez until he tucked the front at the Turn 5 left-hander on the ninth lap.
And right after his teammate fell, Lorenzo began to check out, remaining in the low 1m40s margin while Marquez's pace dropped off.
Lorenzo's lead was up to a second and a half as the raced passed its halfway point, and he managed it from there to the chequered flag, winning by 4.4s.
Rossi had a lonely race en route to his fourth third-place finish of 2018, breaking away with ease from the riders behind him but unable to keep up with the leaders.
LCR Honda's Cal Crutchlow fought through from 10th to fourth, picking off Honda works rider Dani Pedrosa at the Turn 4 right-hander in the second half of the race.
Rossi's teammate Maverick Vinales had plummeted down the order after a horrific start, but recovered to sixth behind Pedrosa, having prevailed in a race-long battle with fellow Yamaha rider Johann Zarco.
Pramac's Danilo Petrucci was ninth, ahead of fellow Ducati satellite rider Alvaro Bautista and Iannone, who struggled noticeably to stay on track in the race.
Pol Espargaro, Scott Redding and Karel Abraham completed the finishers, while Franco Morbidelli was classified 14th after crashing and remounting to retire in the pits.
KTM and Suzuki's respective wildcards Mika Kallio and Sylvain Guintoli had set the tone for the race by crashing early on, with Tom Luthi, Xavier Simeon, Aleix Espargaro and Hafizh Syahrin suffering standalone falls.
LCR Honda's Takaaki Nakagami lost it at Turn 5, his bike wiping out the KTM of Bradley Smith, who had run as high as eighth early on.
Pramac's Jack Miller and Suzuki's Alex Rins also retired, while Tito Rabat's Avintia-run Ducati GP17 caught fire on the main straight when he was fighting in the top 10.
|14||21||Franco Morbidelli||Honda||21||3 laps|
|55||Hafizh Syahrin||Yamaha||20||4 laps|
|53||Tito Rabat||Ducati||18||6 laps|
|43||Jack Miller||Ducati||17||7 laps|
|38||Bradley Smith||KTM||13||11 laps|
|30||Takaaki Nakagami||Honda||13||11 laps|
|42||Alex Rins||Suzuki||11||13 laps|
|4||Andrea Dovizioso||Ducati||8||16 laps|
|10||Xavier Simeon||Ducati||7||17 laps|
|41||Aleix Espargaro||Aprilia||4||20 laps|
|12||Thomas Luthi||Honda||3||21 laps|
|50||Sylvain Guintoli||Suzuki||2||22 laps|
|36||Mika Kallio||KTM||0||24 laps|