Sebastian Vettel kept the Ferrari on top on day two of the first pre-season test at Jerez.
The German posted a 1:20.984 early in the afternoon but had led pretty much throughout the day as he took two seconds of his fastest time from day one, the four-time champion also completed the second highest number of lap with 89 in all.
It was Sauber who were again a surprise second as their second driver, Felipe Nasr, replicated Marcus Ericsson's late run on the soft compound tyres. The Brazilian was the only man within a second of the Prancing Horse on Monday with Valtteri Bottas claimed third for Williams.
Roller-coaster day for Hamilton
Lewis Hamilton got his first taste of the new Mercedes W06 and following team-mate Nico Rosberg's incredible tally of 157 laps on the opening day, the current world champion found things a little harder on day two.
It looked for a while like Hamilton would canter over the 100-lap mark completing 73 laps by lunchtime, but a water leak quite early in the afternoon ended the Briton's day prematurely - though his eventual total of 91 laps was still the highest achieved all day.
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McLaren struggles continue
Certainly it was many more than McLaren managed as the Woking team continued to struggle with the new Honda power unit.
Jenson Button managed just six laps on Monday with a best of 1:54.655 but what is even more amazing is, following a late rain shower, Sebastian Vettel was lapping around five seconds faster than Fernando Alonso's fastest time in the dry on Sunday.
While it was always expected McLaren would lag behind their rivals in terms of time out on track there must be some concern at just how little track running has been done especially considering the time and data Honda had to develop their new power unit since their début in Abu Dhabi last year.
Lotus make 2015 début
Lotus made their first appearance of 2015 with Pastor Maldonado behind the wheel of the E23.
The Enstone team missed Sunday as the car was flown from their factory to the Spanish circuit, but after an overnight build, were able to hit the track fairly early and completed a pleasing 41 laps in total before their day was brought to an end early as a drivetrain issue caused the only red flag on the day.
It was a good day for the rookies on Monday, as mentioned Felipe Nasr took second quickest on his first outing for Sauber and also completed 89 laps as for the former GP2 runner-up got to grips with the C34.
Also making his 2015 bow was 17-year-old Max Verstappen, as the much talked about Dutchman climbed aboard the Toro Rosso.
The son of former F1 driver Jos Verstappen continued to show the calmness and ease he had during his first three outings for the junior Red Bull team last year managing 73 laps in both wet and dry conditions in what was a productive day for the team and the teenager.
Kvyat error costs Red Bull
Things didn't go quite so smoothly at the main Red Bull team, however, as Daniil Kvyat, making his début for the team, made a small error on his first quick lap, damaged the only front wing the team has in Jerez and was forced to complete a number of single lap runs without the wing for the rest of the day.
The Russian did manage 18 laps in all but without one of the most important parts of the car was unable to set a time.
A new front wing is being sent from Milton Keynes and Red Bull will hope to make up for lose time on Tuesday.
Two days in and while again very little should be read into the lap times, the combination of consistent pace and good reliability does bode well for Ferrari going forward.
Vettel will now hand over to his new team-mate Kimi Raikkonen and it will be interesting to see how the 'Iceman' approaches testing given Sebastian's achievements.
Mercedes shouldn't worry too much about the issue that ended Hamilton's day early, they are common in the first days of testing and Hamilton himself has a history of things not going strictly to plan on his first day in a new car.
Red Bull & McLaren must do better
The main concerns instead should be for Red Bull who, despite claiming they are easing the RB11 into service, would have been expected to have done more, the mistake from Kvyat highlights his inexperience but when you're in a top team those kind of errors should not be acceptable, particularly so early on your first day.
And McLaren too will be desperate to complete some multi-lap stints and at least give the drivers a feel for the MP4-30.
That said their plight does seem remarkably similar to that of Red Bull last year and we remember where they were come the opening day in Australia.
A fascinating final two days awaits in Jerez.