Motorcycle champion Sunderland out of Dakar on opening stage
The Briton, who also won the event on two wheels in 2017, has now failed to finish the endurance rally six times out of 10 starts.
The 33-year-old GasGas rider was 10th fastest in Saturday's prologue and fastest at the first checkpoint before falling at the 52km mark in the 368km special stage inland and along the shores of the Red Sea.
Suffering from back pain, he was flown to Yanbu for medical attention.
American Ricky Brabec took his ninth career stage win to lead the motorcycle standings with compatriot Mason Klein denied a first victory after being penalised for speeding.
Honda rider Brabec was 19 seconds clear of Argentina's Kevin Benavides on a KTM with Australian Toby Price third.
In the car category, Spaniard Carlos Sainz took his 42nd career stage win to lead for Audi -- 10 seconds clear of France's nine-times world rally champion Sebastien Loeb for the Bahrain Raid Xtreme team.
Saudi Arabian driver Yazeed al Rajhi was in third place for Overdrive Racing.
Sainz said he had taken it cautiously after suffering an early puncture on the stony terrain. He was watched by his visiting Formula One driver son and namesake.
"It was a good stage, a clear stage for us. No mistakes, no punctures," said Loeb.
Sweden's Mattias Ekstroem, who had been fastest for Audi in Saturday's prologue, led from the first checkpoint but ended up 33 seconds down on Sainz with an additional 15 minute penalty.
Qatar's reigning champion Nasser al Attiyah was sixth overall for Toyota.
The 45th edition of the Dakar is held entirely in Saudi Arabia for the fourth time and ends in Dammam on the Gulf coast on Jan. 15.