Finland's Kimi Raikkonen showed promising signs for Ferrari by outpacing a Lewis Hamilton bruised by Formula One's more powerful cars for the 2017 season in Tuesday's second day of pre-season testing in Barcelona.

The greater speed afforded by radical rules changes showed when Raikkonen posted a best time of 1min 20.960sec for a lap at the Circuit de Catalunya circuit since 2013.

Even more encouragingly for Ferrari, Raikkonen's time came on a slower soft tyre compound to the supersofts Hamilton used in posting his best effort of 1min 20.983sec.

However, Mercedes, who have won the last three drivers' and constructors' world championships, remained out in front when it came to mileage.

Hamilton managed 68 laps in the morning session before handing over the reins of the Mercedes W08 to new teammate Valtteri Bottas.

"I'm finding the car is much more physical to drive than in the past. It’s so much faster in the corners," said Hamilton.

"The force you feel on your body and on your neck is much higher. I've got bruises and bumps where I've never really had them before.

"Physically I feel fine, though, as it’s only half a day of testing. I’ve trained enough over the winter to be ready for more."

Bottas didn't trouble the top of the timesheets with only the seventh fastest lap, but did log an impressive 102 laps in just a few hours.

The former Williams driver even shrugged off a minor spin to complete a full race simulation.

"I had a small off but it wasn’t anything serious," said Bottas.

"I lost the rear end with a gust of tail wind that was quite sudden. This is testing – you need to find the limits."

That sort of reliability is something the beleaguered McLaren-Honda team can only dream of as they suffered another day dogged by reliability problems.

Belgian rookie Stoffel Vandoorne managed just 40 laps to add to the limited 29 former world champion Fernando Alonso completed on Monday.

Vandoorne also had to have the power unit completely replaced on his MCL32.

Only Williams suffered a more disappointing day as Canadian Lance Stroll registered just 12 laps before a spin into the gravel brought a premature end to his day before lunch.

Dutch wonder kid Max Verstappen had a quietly effective day for Red Bull with the third fastest time and 89 laps, albeit well over a second behind Raikkonen and Hamilton.

"For us it's not about showing how quick we can be at the moment," said Verstappen.

"It's the first test week and the second day, so it's much more important to get some mileage in and to check if all the parts are okay.

"The speed difference compared to the cars from last year is a good step; it's definitely more enjoyable through the faster corners."

Red Bull were the only team to deny Mercedes a clean sweep of 21 race victories last season as Verstappen and Daniel Ricciardo claimed one won apiece at the Spanish and Malaysian Grand Prixs respectively.

And Ricciardo believes Mercedes can be beaten this season.

"We can beat them," the Australian told Sky Sports. "We've got the same set of rules as everybody else so there's no reason why we can't across the course of the season."