Under the red-hot Spanish sun, both drivers were fresh out the blocks in the morning session running a series of aero tests on the Renault R.S.20.
Both drivers reported quite low grip during Free Practice 1 with attention for the afternoon geared towards learning more on high fuel and answering questions on predicted race strategy.
Daniel's Soft tyre run midway through the session was good enough for fourth place with Esteban - also on Softs - half a second adrift, but still comfortably inside the top ten.
Conditions are hot here but consistent for the rest of the weekend. We ran smoothly throughout the day with more to find ahead of qualifying.
Daniel Ricciardo: "It's been a pretty good day for us, especially the afternoon's running. On the timesheets, at least, it's another decent Friday: third last week, fourth today, so we'll try and keep that going. Our long run was looking quite competitive as well. I wasn't too happy with the car in the morning, but we made a good step in the afternoon, similar to Silverstone last week. The tricky thing here is the heat. We haven't driven here in the heat for so long and it's completely different to what we felt at winter testing. We're trying to understand that, but we got a better grasp on it this afternoon with the tyres in a better place. We have more work to do before tomorrow, but we'll aim to put in a good one."
Esteban Ocon: "It's not been an easy day, but nevertheless, we'll work hard tonight and find some solutions. Conditions are very warm here and that doesn't make things easy. On our side, we have a bit of work to do at the moment, especially on car behaviour and finding some consistency. It was a little challenging to drive - especially with rear stability - and we're not on top of the issue from Silverstone yet. The good thing is that the car has great pace and we just need to unlock it. Physically, a tough day too in the heat but I'm feeling fine and ready for tomorrow."
Ciaron Pilbeam, Chief Race Engineer: "We've had a smooth day's running with both cars getting through their programmes without any hiccups. We've looked at all three tyre compounds this afternoon between the cars with the usual analysis to follow. Daniel's Soft tyre run certainly looked quite competitive. Esteban, meanwhile, has been less happy in the car all day, so we've got some digging to do tonight to find the cause of that. It seems to be the same issue throughout the day more or less. That aside, it's been good day's running and the conditions look to stay the same for the rest of the weekend. We have more to build on from today."