British motorcyclist Sam Sunderland was Friday promoted to fifth stage winner on the Dakar Rally after sportingly stopping mid-race to help a fellow rider who had fallen and suffered a head injury.

Frenchman Xavier de Soultrait, on a Yamaha, had been the first across the line on the run from Moquegua to Arequipa while Sunderland, on a KTM, finished down in 14th place, 7min 29sec behind.

However, the 29-year-old 2017 Dakar champion lost more than 10 minutes when he gallantly stopped racing to come to the aid of Portugal's Honda rider Paulo Goncalves who was injured in a fall after 155km of the stage.

Goncalves suffered a head injury and a broken right hand, forcing him into the fifth retirement of his Dakar career.

Organisers said stewards decided to hand Sunderland back the 10 minutes he spent at the Portuguese rider's side, thus making him the stage winner by a margin of 3min 23sec.

In the overall standings, America's Ricky Brabec, on a Honda, leads Sunderland by 59sec with Chile's Pablo Quintanilla, riding a Husqvarna, at 2min 52sec back as the event heads into a rest day on Saturday.

"It was a mass start day and there was not much to win or lose, but it was unfortunate for Goncalves and I stopped with him," said Sunderland.

"I stopped for a long time with him, maybe ten minutes, I'm not sure.

"Then I was back with all the other guys in the dust. I didn't have any reference of how much time I was losing, so I was thinking that my race was going downhill."

On the 714km marathon auto race Friday, nine-time world rally champion Sebastien Loeb claimed the honours in a private entry Peugeot for his second stage win of this year's edition.

Loeb finished more than 10 minutes in front of two-time Dakar champion and overnight leader Nasser al-Attiyah of Qatar in a Toyota and 24min 04sec ahead of Spain's Nani Roma in a Mini.

"It was a beautiful stage and we attacked strongly," said Loeb who had endured three punctures on Thursday's fourth stage.

Al-Attiyah shrugged off Loeb's performance.

"Sebastien had nothing to lose, he had to push to climb back into the time charts," he said.

"As far as I'm concerned, I think (13-time winner) Stephane Peterhansel is the dangerman."

However, Peterhansel is now 24 minutes behind al-Attiyah in the title race after a fourth-place finish on Friday, 26 minutes back from Loeb and 16 off his Qatari rival.

It was a disastrous day for Peterhansel whose car became ensnared in binding 'fesh fesh' dune grass and had to be towed out by Roma.