Sainz, who last won a world rally event more than two years ago, set the early pace. He stormed to seven stage wins out of nine with other drivers faltering in temperatures of up to 30 degrees Celsius.
The Ford driver encountered few problems throughout the day, powering through the twisty, dusty runs to finish the leg more than a minute clear of Frenchman Francois Delecour.
“I learned the stages very quickly and the roads were not as bad as we thought. The loose gravel makes it very difficult but running first on the second leg shouldn’t be a problem,” Sainz said.
Gronholm, driving a Peugeot, immediately struggled to make an impact on the race.
He was down in fourth place when he retired with electrical problems on the sixth stage.
“It’s very frustrating and it’s not so good for the championship but my rivals must finish the rally first and even then perhaps Carlos or Francois can take some points off them,” Gronholm said.
Peugeot team mate Delecour was fortunate to remain in second spot after running out of fuel before the final service.