Al-Rajhi dropped out of the fight for victory when he crashed into a dune at the start of the 48-hour chrono stage, suffering severe damage to his Toyota Hilux.
The Saudi’s troubles worked a treat for Sainz, who had already jumped Nasser Al-Attiyah in the early hours of the day, to reclaim the lead in the overall standings on an exceptionally strong day for Audi.
The 48-hour chrono stage that began on Thursday is a new innovation by Dakar organiser ASO in which drivers have to complete a distance of 549km (shortened from 579km) over two days without receiving any external assistance from their teams.
But instead of the schedule simply being divided into two days based on distance, drivers have to cover as much ground as they possibly can before 4pm, before halting at the next available bivouac.
With seven biouvacs spread over hundreds of kilometres, and each driver setting off for the stage at a different time, that meant that not everyone ended up at the same halting spot for the night.
Although Sainz only made it as far as Bivouac D, he was still the provisional stage and overall leader at the end of the day, having covered the first 398km with a time of 5h22m00s.
Sainz led from the very front in Empty Quarter, one of the world’s largest sand deserts, slowly but steadily extending his lead over the chasing pack led by team-mate Stephane Peterhansel and then Mattias Ekstrom.
At one point, Sainz’s advantage to Ekstrom stretched to over five minutes, but the Swede was able to cut the back in the final sections to end up 4m31s adrift at Bivouac D.
Source: Autosport