The 57-year-old Mini driver clocked 2hr 03min 43sec on a stage shortened by high winds to a 233km special between Haradh and Shubaytah, finishing ahead of Poland’s Jakub Przygonski (mini) and South African Giniel de Villier (Toyota).
Sainz took full advantage of navigational problems by closest rivals Nasser Al-Attiyah, the defending champion, and France’s ‘Mr. Dakar’, Stephane Peterhansel.
Peterhansel, who has won the Dakar 13 times (seven times in a car and six times on a bike), finished 11min 48sec off Sainz’s pace, while Qatar’s Al-Attiyah was further back, at 17:46.
The result means Sainz, with two stages to go, now sits 18:10 ahead of Al-Attiyah and 18:26 in front of Peterhansel.
“It was a dangerous stage with lots of difficult dunes,” Peterhansel said.
“Several kilometres before the neutralised section, we got completely lost with Nasser and other drivers. Some drivers got there at the right time, when we eventually found the right way and gained a lot of time.
“In the end, it’s a good stage for my team-mate Carlos who has opened up a gap on Nasser, whilst we have got a bit closer to Nasser even if we are still in third position.”
Dakar debutant Fernando Alonso, the two-time former Formula One champion, lost more than an hour after double rolling his Toyota, an accident that saw the Spaniard carry on driving with no windscreen.
American Ricky Brabec increased his lead in the general standings of the motorbike category with a second-placed finish.
The HRC rider now leads Chilean Pablo Quintanilla (Husqvarna) by 25 minutes and stage winner Joan Barreda of Spain by 27 minutes.
Thursday’s penultimate stage 11 sees competitors negotiate 744km, featuring a 379km special, from Shubaytah back to Haradh.