Ferrari and Mercedes topped the time sheets on Monday as the first day of Formula One pre-season testing got underway in Barcelona and the world's best drivers returned to the track in preparation for the new campaign.
Sebastian Vettel ended the session with the quickest time, clocking a 1:24.939, while defending world champion Lewis Hamilton wasn't far behind, nearly half a second adrift of the German. Mercedes seemed to focus on completing long runs, however, sacrificing times for information on their new car and more than 150 laps (600 kilometres) in the bag.
Hamilton's team-mate Nico Rosberg will also have his chance to properly test out the new W07 Hybrid, but for now, it's the reigning champion who looks in good shape to mount another world-title challenge in 2016.
Jenson Button made a late charge to make a dent on Monday's fastest finishers, and Valtteri Bottas made sure Williams kept pressure high among the quickest teams on Day 1. Here's a look at the fastest times, courtesy of Formula One's official Twitter account:
A quality-over-quantity approach appeared to do the trick for leader Vettel on Monday, whose morning time of 1:24.939 was enough to see him through to end of the day still topping the leaderboard.
Despite how mighty that finish was, however, the PitCrew Online agreed the sheer volume of testing undergone by Hamilton's Mercedes was perhaps the real headline, racking up 156 laps in total:
By all accounts, it seems as though Ferrari could well be the nearest challenge to Mercedes this season, as many had already envisioned ticking toward this new term.
Mercedes chief Toto Wolff would have undoubtedly been pleased for Hamilton's display, but he even went on to speak positively about the competition Ferrari are readying, per Sky Sports F1:
Red Bull's Daniel Ricciardo finished Monday's testing session in third with a time of 1:26.044, while 19-year-old Alfonso Celis, Force India's development driver, was something of a surprise finisher in fifth.
Britain's Button also surprised as he managed to not only record an impressive 84 laps but also notch an admirable lap time of 1:26.735 for McLaren, per the official Formula One Twitter account:
Simmering temperatures in the latter half of Monday's testing session meant some manufacturers weren't as eager to work into the later hours, but Hamilton's Mercedes team-mate Rosberg wasn't among those.
Rosberg may not have been able to challenge Hamilton directly on Monday, but the German posted evidence of his excitement to get going again via Twitter:
Fans shouldn't read too much into the times every driver registers during pre-season testing, and particularly during the first days. Per BBC Sport's Lawrence Barretto, Ferrari dominated Mercedes during the first day last year, and it was hardly indicative of how the season would play out.
If you needed further proof of how the timesheets should be taken with a grain of salt, take a look at this peculiar setup the Scuderia came out with to start the day, courtesy of Sky Sports F1:
That's not to say fans should ignore pre-season testing altogether. There are always plenty of lessons to learn, and Monday's opening session was no different.
For starters, it looks as if the battle between Vettel and Hamilton could be a good one. The two exchanged top times throughout the day, although the Ferrari always looked a fraction faster than the Mercedes. Hamilton clocked over 50 rounds during the morning session, a sign reliability shouldn't be an issue for the German manufacturer.
Per BBC Sport's Andrew Benson, Hamilton said in a Mercedes team statement he isn't too worried about team-mate Nico Rosberg, who looked very solid in the last few races of the 2015 campaign:
I'm not really too fussed about what happened in the final few races of 2015 as it didn't affect my championship.
Of course, I love winning and that's always the goal - but to be honest my attention was elsewhere at that point. It had been such a successful season and you can't win them all, so that was my feeling at the end of the year. If anything, it motivated me. It made me think OK, next year Nico is going to be super-quick and super-strong, so I've got to make sure I raise the bar again." That's the big question - how do you do that? I've achieved it in each of the last two years - but to do it again for a third time will be tough, no doubt. That's the unknown - but I've been in the simulator recently and thankfully I can still drive, so that's a start!
But Vettel might provide the defending champion with just as big a challenge. Ferrari made some positive steps in 2015, and the new SF16-H car made a strong impression on Monday, clocking 32 laps.
Ferrari and Mercedes aren't the only manufacturers who should feel good about their first session of pre-season testing, however. All 11 cars saw the track on Monday, and with the exception of Wehrlein, every driver managed 13 laps or more before the lunch break.
For teams like McLaren, who struggled tremendously in pre-season testing last year, or newcomers Haas, the fact their cars were able to clock relatively competitive times is encouraging.
F1's official Twitter account shared footage of Haas' debut in Barcelona:
The team did run into a bit of trouble, as Romain Grosjean's front wing came off at one point, per F1's official Twitter account:
Despite the high-octane action of Grands Prix, Formula One success if more like a marathon than a sprint, and the top teams in the world are back preparing for another top-class campaign after months of waiting.