Sainz logged 151 laps around Circuit de Barcelona-Catalunya during the first week of testing, which was disrupted by rain and snow.

At the conclusion of the week, Sainz conceded he “pretty much” felt like he had completed no more than a single proper test day – but said he was convinced of his new Renault RS18 car's “very big potential.”

“I haven't tested yet,” Sainz said. “I have run but I haven't really started testing the car, setting it up for my liking, going in one direction, the other.”

“I haven't felt fully at home yet in the car but that's why I think we have still very big potential ahead of us.

“If we start doing things properly and we start testing and we start going in the right direction, I have still big margins of improvement to be more comfortable in the car.”

The Spaniard's best laptime on Thursday – 1m20.940s, 1.6s off pace-setter Lewis Hamilton – came on mediums, and he took encouragement from how the new car behaved on the compound.

"To get the medium to work is a positive sign, there's not many teams out there who are really running the medium, and today we managed to switch on the medium and do a good long run on it.

“Balance-wise, still not there, still we have huge margins of improvement, so I'm going to be patient, wait for next week.”

Sainz said he felt settled in at Renault – having joined from Toro Rosso late last season - but stressed the importance of getting more testing miles under his belt and setting up the RS18 to his liking in time for the season opener in Melbourne.

“The last four races last year helped to get to know everyone [at Renault] and to give my feedback regarding last year’s car,” he said.

“And now I just need testing, because racing is not the same as testing. Actually, my father always told me that where you win the races is in testing.

“And I hadn’t had the chance yet to really test the car, follow different directions.

“Normally Melbourne has been a good race for me. I think [it's] because I've come up from the last day of testing with a good baseline on the car that gives me confidence and I managed to attack the streets of Melbourne how I like.

“It's not an easy track to go there for the first time in a year, you need really big confidence with the car.”

Despite the weather-induced setbacks, the Spaniard believes the second test week in Barcelona should prove sufficient for him to be properly prepared for the Australian Grand Prix – provided that he is allowed trouble-free running.

“I think I have time, personally,” he said. “I don't know the others, but I think if we have a clean week, I have time to do some maybe shorter runs and go through more tyres and just go in different directions.

"I think I have time, but then we will need a clean week.”

Additional reporting by Oleg Karpov