Alex Marquez narrowly defeated Pedro Acosta in a thrilling Portuguese Grand Prix MotoGP sprint at Portimao.

Fifth on the grid after a crash in qualifying, Marquez was up to third immediately off the line - picking off Pecco Bagnaia and Fabio Quartararo - and settled in behind race leader Marco Bezzecchi and Acosta as the trio made a breakaway.

Acosta drafted past Bezzecchi on the main straight at the start of the third lap, but could not build a buffer - though a possible Bezzecchi counter-attack on the main straight the following lap became a Marquez overtake on Bezzecchi instead.

The first sector has been Acosta's big strength through the weekend so far, and the final sector has been Marquez's, and this played out in an exhilarating battle over the next few laps.

As Marquez set up and pulled off a move out of the final corner to start lap six of 12, Acosta attempted an immediate counter-attack, failed, and yet remained close enough to try again at the sharp Turn 5 - this time succeeding.

Two laps later Marquez went past again on the main straight, and Acosta retaliated again at Turn 5. But after moving past for the third time Marquez finally established enough of a buffer to stay ahead at Turn 5 - despite running wide at the corner.

It looked at that point as if Acosta would have to switch his attention to defending second from Bezzecchi, yet that only lasted a couple of laps - and the KTM man instead came back at Marquez, ending up just 0.120s off at the finish.

Yamaha rider Quartararo converted a front row into fourth place, riding a relatively lonely race as Ducati duo Pecco Bagnaia and Fabio Di Giannantonio duelled for fifth behind him.

But once Di Giannantonio went past Bagnaia's pace fell apart and he fell into the clutches of a group of pursuers, who he was fending off successfully until the very final corner.

A charging Fermin Aldeguer grew alongside to claim sixth, and Bagnaia also had a wheelie right before the finish line that allowed Johann Zarco - overtaken by Aldeguer just prior - to claim seventh.

Bagnaia's eighth place means he has dropped 10 back from Bezzecchi in the fight for third in the championship.

Brad Binder salvaged a single point for ninth ahead of his part-time KTM stablemate Pol Espargaro.

There were three retirements from the race, with debutant Nicolo Bulega - standing in for the injured champion Marc Marquez - crashing out of 17th, while both Joan Mir and Somkiat Chantra parked up in the pits, with Mir hindered by what looked like a technical issue already off the start.

Results

1 Alex Marquez (Gresini Ducati)
2 Pedro Acosta (KTM) +0.120s
3 Marco Bezzecchi (Aprilia) +0.637s
4 Fabio Quartararo (Yamaha) +5.276s
5 Fabio Di Giannantonio (VR46 Ducati) +6.088s
6 Fermin Aldeguer (Gresini Ducati) +8.864s
7 Johann Zarco (LCR Honda) +8.886s
8 Pecco Bagnaia (Ducati) +8.898s
9 Brad Binder (KTM) +9.052s
10 Pol Espargaro (Tech3 KTM) +10.121s
11 Ai Ogura (Trackhouse Aprilia) +10.290s
12 Luca Marini (Honda) +12.016s
13 Enea Bastianini (Tech3 KTM) +13.469s
14 Jack Miller (Pramac Yamaha) +13.900s
15 Franco Morbidelli (VR46 Ducati) +14.520s
16 Miguel Oliveira (Pramac Yamaha) +15.289s
17 Alex Rins (Yamaha) +22.861s
18 Lorenzo Savadori (Aprilia) +25.456s
DNF Nicolo Bulega (Ducati)
DNF Joan Mir (Honda)
DNF Somkiat Chantra (LCR Honda)