World champion Marc Marquez lapped under the official race lap record as he finished day one of the French MotoGP just 0.007s ahead of Andrea Iannone.
However the Ducati rider was using the extra-soft rear tyre while Repsol Honda's Marquez, like third fastest Alvaro Bautista (Gresini Honda), ran the soft compound.
"I felt comfortable right from the start today," said Marquez, quickest in both sessions. "We began with the base set-up from Jerez and worked from there. In the afternoon we tried things out with the tyres and tweaked the set-up further to keep going forward.
"Besides being the fastest over a single lap, our pace was also really good today, so I am happy with how everything went in general. Tomorrow we shall try to do even better, because I'm sure that the rest of the riders will take another step forward."
Marquez, who signed a new two year Honda contract earlier this week, is undefeated in qualifying and races this year, allowing him to build a 28 point lead over team-mate Dani Pedrosa after four rounds.
Marquez and Pedrosa both also tried the harder (medium) compound rear tyre during the afternoon, but preferred the soft rubber.
"We tried both tyres but today the sort was working better, but we will try again tomorrow when there is more rubber on the track," said Marquez.
Pedrosa was riding for the first time since undergoing arm pump surgery and finished the day in fifth position (+0.490s), albeit having set his best time during a long nine-lap run.
“Today was basically a day to see what kind of shape I am in, and it went well,” declared Pedrosa, winner of last year's wet race. “For the first time using my arm in ten days, the feeling is okay. It's a little sore and swollen. I took things carefully and didn't push too much, because I didn't want to go 100% too soon. The initial feeling was pretty good, and we hope that things will improve further overnight.
“In theory today should be the toughest day, and I hope to be better tomorrow. On track I focused on putting in a lot of laps, but without making too many changes to the bike. We basically tried out the tyres, and at the moment the soft option seems to be the most adequate.”